@article{ReeveNicholsonAltafetal.2022,
  author    = {Reeve, Holly A. and Nicholson, Jake and Altaf, Farieha and Lonsdale, Thomas H. and Preissler, Janina and Lauterbach, Lars and Lenz, Oliver and Leimk{\"u}hler, Silke and Hollmann, Frank and Paul, Caroline E. and Vincent, Kylie A.},
  title     = {A hydrogen-driven biocatalytic approach to recycling synthetic analogues of NAD(P)H},
  series = {Chemical communications : ChemComm},
  volume    = {58},
  journal   = {Chemical communications : ChemComm},
  number    = {75},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1359-7345},
  doi       = {10.1039/d2cc02411j},
  pages     = {10540 -- 10543},
  year      = {2022},
  abstract  = {We demonstrate a recycling system for synthetic nicotinamide cofactor analogues using a soluble hydrogenase with turnover number of >1000 for reduction of the cofactor analogues by H-2. Coupling this system to an ene reductase, we show quantitative conversion of N-ethylmaleimide to N-ethylsuccinimide. The biocatalyst system retained >50\% activity after 7 h.},
  language  = {en}
}
@article{TeraoGarattiniRomaoetal.2020,
  author    = {Terao, Mineko and Garattini, Enrico and Rom{\~a}o, Maria Jo{\~a}o and Leimk{\"u}hler, Silke},
  title     = {Evolution, expression, and substrate specificities of aldehyde oxidase enzymes in eukaryotes},
  series = {The journal of biological chemistry},
  volume    = {295},
  journal   = {The journal of biological chemistry},
  number    = {16},
  publisher = {American Society for Biochemistry and Molecular Biology},
  address   = {Rockville},
  issn      = {0021-9258},
  doi       = {10.1074/jbc.REV119.007741},
  pages     = {5377 -- 5389},
  year      = {2020},
  abstract  = {Aldehyde oxidases (AOXs) are a small group of enzymes belonging to the larger family of molybdo-flavoenzymes, along with the well-characterized xanthine oxidoreductase. The two major types of reactions that are catalyzed by AOXs are the hydroxylation of heterocycles and the oxidation of aldehydes to their corresponding carboxylic acids. Different animal species have different complements of AOX genes. The two extremes are represented in humans and rodents; whereas the human genome contains a single active gene (AOX1), those of rodents, such as mice, are endowed with four genes (Aox1-4), clustering on the same chromosome, each encoding a functionally distinct AOX enzyme. It still remains enigmatic why some species have numerous AOX enzymes, whereas others harbor only one functional enzyme. At present, little is known about the physiological relevance of AOX enzymes in humans and their additional forms in other mammals. These enzymes are expressed in the liver and play an important role in the metabolisms of drugs and other xenobiotics. In this review, we discuss the expression, tissue-specific roles, and substrate specificities of the different mammalian AOX enzymes and highlight insights into their physiological roles.},
  language  = {en}
}
@misc{Leimkuehler2020,
  author    = {Leimk{\"u}hler, Silke},
  title     = {The biosynthesis of the molybdenum cofactors in Escherichia coli},
  series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {6},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-51655},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-516559},
  pages     = {22},
  year      = {2020},
  abstract  = {The biosynthesis of the molybdenum cofactor (Moco) is highly conserved among all kingdoms of life. In all molybdoenzymes containing Moco, the molybdenum atom is coordinated to a dithiolene group present in the pterin-based 6-alkyl side chain of molybdopterin (MPT). In general, the biosynthesis of Moco can be divided into four steps in in bacteria: (i) the starting point is the formation of the cyclic pyranopterin monophosphate (cPMP) from 5 '-GTP, (ii) in the second step the two sulfur atoms are inserted into cPMP leading to the formation of MPT, (iii) in the third step the molybdenum atom is inserted into MPT to form Moco and (iv) in the fourth step bis-Mo-MPT is formed and an additional modification of Moco is possible with the attachment of a nucleotide (CMP or GMP) to the phosphate group of MPT, forming the dinucleotide variants of Moco. This review presents an update on the well-characterized Moco biosynthesis in the model organism Escherichia coli including novel discoveries from the recent years.},
  language  = {en}
}
@article{YanFrokjarEngelbrektetal.2021,
  author    = {Yan, Jiawei and Fr{\o}kj{\ae}r, Emil Egede and Engelbrekt, Christian and Leimk{\"u}hler, Silke and Ulstrup, Jens and Wollenberger, Ulla and Xiao, Xinxin and Zhang, Jingdong},
  title     = {Voltammetry and single-molecule in situ scanning tunnelling microscopy of the redox metalloenzyme human sulfite oxidase},
  series = {ChemElectroChem},
  volume    = {8},
  journal   = {ChemElectroChem},
  number    = {1},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {2196-0216},
  doi       = {10.1002/celc.202001258},
  pages     = {164 -- 171},
  year      = {2021},
  abstract  = {Human sulfite oxidase (hSO) is a homodimeric two-domain enzyme central in the biological sulfur cycle. A pyranopterin molybdenum cofactor (Moco) is the catalytic site and a heme b(5) group located in the N-terminal domain. The two domains are connected by a flexible linker region. Electrons produced at the Moco in sulfite oxidation, are relayed via heme b(5) to electron acceptors or an electrode surface. Inter-domain conformational changes between an open and a closed enzyme conformation, allowing "gated" electron transfer has been suggested. We first recorded cyclic voltammetry (CV) of hSO on single-crystal Au(111)-electrode surfaces modified by self-assembled monolayers (SAMs) both of a short rigid thiol, cysteamine and of a longer structurally flexible thiol, omega-amino-octanethiol (AOT). hSO on cysteamine SAMs displays a well-defined pair of voltammetric peaks around -0.207 V vs. SCE in the absence of sulfite substrate, but no electrocatalysis. hSO on AOT SAMs displays well-defined electrocatalysis, but only "fair" quality voltammetry in the absence of sulfite. We recorded next in situ scanning tunnelling spectroscopy (STS) of hSO on AOT modified Au(111)-electrodes, disclosing, a 2-5 \% surface coverage of strong molecular scale contrasts, assigned to single hSO molecules, notably with no contrast difference in the absence and presence of sulfite. In situ STS corroborated this observation with a sigmoidal tunnelling current/overpotential correlation.},
  language  = {en}
}
@article{TadjoungWaffoMitrovaTiedemannetal.2021,
  author    = {Tadjoung Waffo, Armel Franklin and Mitrova, Biljana and Tiedemann, Kim and Iobbi-Nivol, Chantal and Leimk{\"u}hler, Silke and Wollenberger, Ulla},
  title     = {Electrochemical trimethylamine n-oxide biosensor with enzyme-based oxygen-scavenging membrane for long-term operation under ambient air},
  series = {Biosensors : open access journal},
  volume    = {11},
  journal   = {Biosensors : open access journal},
  number    = {4},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2079-6374},
  doi       = {10.3390/bios11040098},
  pages     = {17},
  year      = {2021},
  abstract  = {An amperometric trimethylamine N-oxide (TMAO) biosensor is reported, where TMAO reductase (TorA) and glucose oxidase (GOD) and catalase (Cat) were immobilized on the electrode surface, enabling measurements of mediated enzymatic TMAO reduction at low potential under ambient air conditions. The oxygen anti-interference membrane composed of GOD, Cat and polyvinyl alcohol (PVA) hydrogel, together with glucose concentration, was optimized until the O-2 reduction current of a Clark-type electrode was completely suppressed for at least 3 h. For the preparation of the TMAO biosensor, Escherichia coli TorA was purified under anaerobic conditions and immobilized on the surface of a carbon electrode and covered by the optimized O-2 scavenging membrane. The TMAO sensor operates at a potential of -0.8 V vs. Ag/AgCl (1 M KCl), where the reduction of methylviologen (MV) is recorded. The sensor signal depends linearly on TMAO concentrations between 2 mu M and 15 mM, with a sensitivity of 2.75 +/- 1.7 mu A/mM. The developed biosensor is characterized by a response time of about 33 s and an operational stability over 3 weeks. Furthermore, measurements of TMAO concentration were performed in 10\% human serum, where the lowest detectable concentration is of 10 mu M TMAO.},
  language  = {en}
}
@article{LaunDuffusWahlefeldetal.2022,
  author    = {Laun, Konstantin and Duffus, Benjamin R. and Wahlefeld, Stefan and Katz, Sagie and Belger, Dennis Heinz and Hildebrandt, Peter and Mroginski, Maria Andrea and Leimk{\"u}hler, Silke and Zebger, Ingo},
  title     = {Infrared spectroscopy flucidates the inhibitor binding sites in a metal-dependent formate dehydrogenase},
  series = {Chemistry - a European journal},
  journal   = {Chemistry - a European journal},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {0947-6539},
  doi       = {10.1002/chem.202201091},
  pages     = {8},
  year      = {2022},
  abstract  = {Biological carbon dioxide (CO2) reduction is an important step by which organisms form valuable energy-richer molecules required for further metabolic processes. The Mo-dependent formate dehydrogenase (FDH) from Rhodobacter capsulatus catalyzes reversible formate oxidation to CO2 at a bis-molybdopterin guanine dinucleotide (bis-MGD) cofactor. To elucidate potential substrate binding sites relevant for the mechanism, we studied herein the interaction with the inhibitory molecules azide and cyanate, which are isoelectronic to CO2 and charged as formate. We employed infrared (IR) spectroscopy in combination with density functional theory (DFT) and inhibition kinetics. One distinct inhibitory molecule was found to bind to either a non-competitive or a competitive binding site in the secondary coordination sphere of the active site. Site-directed mutagenesis of key amino acid residues in the vicinity of the bis-MGD cofactor revealed changes in both non-competitive and competitive binding, whereby the inhibitor is in case of the latter interaction presumably bound between the cofactor and the adjacent Arg587.},
  language  = {en}
}
@article{StrippDuffusFourmondetal.2022,
  author    = {Stripp, Sven T. and Duffus, Benjamin R. and Fourmond, Vincent and Leger, Christophe and Leimk{\"u}hler, Silke and Hirota, Shun and Hu, Yilin and Jasniewski, Andrew and Ogata, Hideaki and Ribbe, Markus W.},
  title     = {Second and outer coordination sphere effects in nitrogenase, hydrogenase, formate dehydrogenase, and CO dehydrogenase},
  series = {Chemical reviews : CR},
  volume    = {122},
  journal   = {Chemical reviews : CR},
  number    = {14},
  publisher = {American Chemical Society},
  address   = {Washington, DC},
  issn      = {0009-2665},
  doi       = {10.1021/acs.chemrev.1c00914},
  pages     = {11900 -- 11973},
  year      = {2022},
  abstract  = {Gases like H-2, N-2, CO2, and CO are increasingly recognized as critical feedstock in "green" energy conversion and as sources of nitrogen and carbon for the agricultural and chemical sectors. However, the industrial transformation of N-2, CO2, and CO and the production of H-2 require significant energy input, which renders processes like steam reforming and the Haber-Bosch reaction economically and environmentally unviable. Nature, on the other hand, performs similar tasks efficiently at ambient temperature and pressure, exploiting gas-processing metalloenzymes (GPMs) that bind low-valent metal cofactors based on iron, nickel, molybdenum, tungsten, and sulfur. Such systems are studied to understand the biocatalytic principles of gas conversion including N-2 fixation by nitrogenase and H-2 production by hydrogenase as well as CO2 and CO conversion by formate dehydrogenase, carbon monoxide dehydrogenase, and nitrogenase. In this review, we emphasize the importance of the cofactor/protein interface, discussing how second and outer coordination sphere effects determine, modulate, and optimize the catalytic activity of GPMs. These may comprise ionic interactions in the second coordination sphere that shape the electron density distribution across the cofactor, hydrogen bonding changes, and allosteric effects. In the outer coordination sphere, proton transfer and electron transfer are discussed, alongside the role of hydrophobic substrate channels and protein structural changes. Combining the information gained from structural biology, enzyme kinetics, and various spectroscopic techniques, we aim toward a comprehensive understanding of catalysis beyond the first coordination sphere.},
  language  = {en}
}
@article{FujiharaZhangJacksonetal.2022,
  author    = {Fujihara, Kenji M. and Zhang, Bonnie Z. and Jackson, Thomas D. and Ogunkola, Moses and Nijagal, Brunda and Milne, Julia V. and Sallman, David A. and Ang, Ching-Seng and Nikolic, Iva and Kearney, Conor J. and Hogg, Simon J. and Cabalag, Carlos S. and Sutton, Vivien R. and Watt, Sally and Fujihara, Asuka T. and Trapani, Joseph A. and Simpson, Kaylene J. and Stojanovski, Diana and Leimk{\"u}hler, Silke and Haupt, Sue and Phillips, Wayne A. and Clemons, Nicholas J.},
  title     = {Eprenetapopt triggers ferroptosis, inhibits NFS1 cysteine desulfurase, and synergizes with serine and glycine dietary restriction},
  series = {Science Advances},
  volume    = {8},
  journal   = {Science Advances},
  number    = {37},
  publisher = {American Assoc. for the Advancement of Science},
  address   = {Washington},
  issn      = {2375-2548},
  doi       = {10.1126/sciadv.abm9427},
  pages     = {13},
  year      = {2022},
  abstract  = {The mechanism of action of eprenetapopt (APR-246, PRIMA-1MET) as an anticancer agent remains unresolved, al-though the clinical development of eprenetapopt focuses on its reported mechanism of action as a mutant-p53 reactivator. Using unbiased approaches, this study demonstrates that eprenetapopt depletes cellular antioxidant glutathione levels by increasing its turnover, triggering a nonapoptotic, iron-dependent form of cell death known as ferroptosis. Deficiency in genes responsible for supplying cancer cells with the substrates for de novo glutathione synthesis (SLC7A11, SHMT2, and MTHFD1L), as well as the enzymes required to synthesize glutathione (GCLC and GCLM), augments the activity of eprenetapopt. Eprenetapopt also inhibits iron-sulfur cluster biogenesis by limit-ing the cysteine desulfurase activity of NFS1, which potentiates ferroptosis and may restrict cellular proliferation. The combination of eprenetapopt with dietary serine and glycine restriction synergizes to inhibit esophageal xenograft tumor growth. These findings reframe the canonical view of eprenetapopt from a mutant-p53 reactivator to a ferroptosis inducer.},
  language  = {en}
}
@article{DeSousaMotaDinizCoelhoetal.2021,
  author    = {De Sousa Mota, Cristiano and Diniz, Ana and Coelho, Catarina and Santos-Silva, Teresa and Esmaeeli Moghaddam Tabalvandani, Mariam and Leimk{\"u}hler, Silke and Cabrita, Eurico J. and Marcelo, Filipa and Rom{\~a}o, Maria Jo{\~a}o},
  title     = {Interrogating the inhibition mechanisms of human aldehyde oxidase by X-ray crystallography and NMR spectroscopy},
  series = {Journal of medicinal chemistry / American Chemical Society},
  volume    = {64},
  journal   = {Journal of medicinal chemistry / American Chemical Society},
  number    = {17},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0022-2623},
  doi       = {10.1021/acs.jmedchem.1c01125},
  pages     = {13025 -- 13037},
  year      = {2021},
  abstract  = {Human aldehyde oxidase (hAOX1) is mainly present in the liver and has an emerging role in drug metabolism, since it accepts a wide range of molecules as substrates and inhibitors. Herein, we employed an integrative approach by combining NMR, X-ray crystallography, and enzyme inhibition kinetics to understand the inhibition modes of three hAOX1 inhibitors-thioridazine, benzamidine, and raloxifene. These integrative data indicate that thioridazine is a noncompetitive inhibitor, while benzamidine presents a mixed type of inhibition. Additionally, we describe the first crystal structure of hAOX1 in complex with raloxifene. Raloxifene binds tightly at the entrance of the substrate tunnel, stabilizing the flexible entrance gates and elucidating an unusual substrate-dependent mechanism of inhibition with potential impact on drug-drug interactions. This study can be considered as a proof-of-concept for an efficient experimental screening of prospective substrates and inhibitors of hAOX1 relevant in drug discovery.},
  language  = {en}
}
@article{Leimkuehler2021,
  author    = {Leimk{\"u}hler, Silke},
  title     = {Transition metals in catalysis},
  series = {Inorganics : open access journal},
  volume    = {9},
  journal   = {Inorganics : open access journal},
  number    = {1},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2304-6740},
  doi       = {10.3390/inorganics9010006},
  pages     = {2},
  year      = {2021},
  language  = {en}
}
@article{DuffusSchrapersSchuthetal.2020,
  author    = {Duffus, Benjamin R. and Schrapers, Peer and Schuth, Nils and Mebs, Stefan and Dau, Holger and Leimk{\"u}hler, Silke and Haumann, Michael},
  title     = {Anion binding and oxidative modification at the molybdenum cofactor of formate dehydrogenase from Rhodobacter capsulatus studied by X-ray absorption spectroscopy},
  series = {Inorganic chemistry},
  volume    = {59},
  journal   = {Inorganic chemistry},
  number    = {1},
  publisher = {American Chemical Society},
  address   = {Washington, DC},
  issn      = {0020-1669},
  doi       = {10.1021/acs.inorgchem.9b01613},
  pages     = {214 -- 225},
  year      = {2020},
  abstract  = {Formate dehydrogenase (FDH) enzymes are versatile catalysts for CO2 conversion. The FDH from Rhodobacter capsulatus contains a molybdenum cofactor with the dithiolene functions of two pyranopterin guanine dinucleotide molecules, a conserved cysteine, and a sulfido group bound at Mo(VI). In this study, we focused on metal oxidation state and coordination changes in response to exposure to O-2, inhibitory anions, and redox agents using X-ray absorption spectroscopy (XAS) at the Mo K-edge. Differences in the oxidative modification of the bis-molybdopterin guanine dinucleotide (bis-MGD) cofactor relative to samples prepared aerobically without inhibitor, such as variations in the relative numbers of sulfido (Mo=S) and oxo (Mo=O) bonds, were observed in the presence of azide (N-3(-)) or cyanate (OCN-). Azide provided best protection against O-2, resulting in a quantitatively sulfurated cofactor with a displaced cysteine ligand and optimized formate oxidation activity. Replacement of the cysteine ligand by a formate (HCO2-) ligand at the molybdenum in active enzyme is compatible with our XAS data. Cyanide (CN-) inactivated the enzyme by replacing the sulfido ligand at Mo(VI) with an oxo ligand. Evidence that the sulfido group may become protonated upon molybdenum reduction was obtained. Our results emphasize the role of coordination flexibility at the molybdenum center during inhibitory and catalytic processes of FDH enzymes.},
  language  = {en}
}
@article{MendelHercherZupoketal.2020,
  author    = {Mendel, Ralf R. and Hercher, Thomas W. and Zupok, Arkadiusz and Hasnat, Muhammad Abrar and Leimk{\"u}hler, Silke},
  title     = {The requirement of inorganic Fe-S clusters for the biosynthesis of the organometallic molybdenum cofactor},
  series = {Inorganics : open access journal},
  volume    = {8},
  journal   = {Inorganics : open access journal},
  number    = {7},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2304-6740},
  doi       = {10.3390/inorganics8070043},
  pages     = {23},
  year      = {2020},
  abstract  = {Iron-sulfur (Fe-S) clusters are essential protein cofactors. In enzymes, they are present either in the rhombic [2Fe-2S] or the cubic [4Fe-4S] form, where they are involved in catalysis and electron transfer and in the biosynthesis of metal-containing prosthetic groups like the molybdenum cofactor (Moco). Here, we give an overview of the assembly of Fe-S clusters in bacteria and humans and present their connection to the Moco biosynthesis pathway. In all organisms, Fe-S cluster assembly starts with the abstraction of sulfur froml-cysteine and its transfer to a scaffold protein. After formation, Fe-S clusters are transferred to carrier proteins that insert them into recipient apo-proteins. In eukaryotes like humans and plants, Fe-S cluster assembly takes place both in mitochondria and in the cytosol. Both Moco biosynthesis and Fe-S cluster assembly are highly conserved among all kingdoms of life. Moco is a tricyclic pterin compound with molybdenum coordinated through its unique dithiolene group. Moco biosynthesis begins in the mitochondria in a Fe-S cluster dependent step involving radical/S-adenosylmethionine (SAM) chemistry. An intermediate is transferred to the cytosol where the dithiolene group is formed, to which molybdenum is finally added. Further connections between Fe-S cluster assembly and Moco biosynthesis are discussed in detail.},
  language  = {en}
}
@misc{OgunkolaGuiraudieCaprazFeronetal.2023,
  author    = {Ogunkola, Moses Olalekan and Guiraudie-Capraz, Gaelle and F{\´e}ron, Fran{\c{c}}ois and Leimk{\"u}hler, Silke},
  title     = {The Human Mercaptopyruvate Sulfurtransferase TUM1 Is Involved in Moco Biosynthesis, Cytosolic tRNA Thiolation and Cellular Bioenergetics in Human Embryonic Kidney Cells},
  series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {1307},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-57958},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-579580},
  pages     = {23},
  year      = {2023},
  abstract  = {Sulfur is an important element that is incorporated into many biomolecules in humans. The incorporation and transfer of sulfur into biomolecules is, however, facilitated by a series of different sulfurtransferases. Among these sulfurtransferases is the human mercaptopyruvate sulfurtransferase (MPST) also designated as tRNA thiouridine modification protein (TUM1). The role of the human TUM1 protein has been suggested in a wide range of physiological processes in the cell among which are but not limited to involvement in Molybdenum cofactor (Moco) biosynthesis, cytosolic tRNA thiolation and generation of H2S as signaling molecule both in mitochondria and the cytosol. Previous interaction studies showed that TUM1 interacts with the L-cysteine desulfurase NFS1 and the Molybdenum cofactor biosynthesis protein 3 (MOCS3). Here, we show the roles of TUM1 in human cells using CRISPR/Cas9 genetically modified Human Embryonic Kidney cells. Here, we show that TUM1 is involved in the sulfur transfer for Molybdenum cofactor synthesis and tRNA thiomodification by spectrophotometric measurement of the activity of sulfite oxidase and liquid chromatography quantification of the level of sulfur-modified tRNA. Further, we show that TUM1 has a role in hydrogen sulfide production and cellular bioenergetics.},
  language  = {en}
}
@article{OgunkolaGuiraudieCaprazFeronetal.2023,
  author    = {Ogunkola, Moses Olalekan and Guiraudie-Capraz, Gaelle and F{\´e}ron, Fran{\c{c}}ois and Leimk{\"u}hler, Silke},
  title     = {The Human Mercaptopyruvate Sulfurtransferase TUM1 Is Involved in Moco Biosynthesis, Cytosolic tRNA Thiolation and Cellular Bioenergetics in Human Embryonic Kidney Cells},
  series = {Biomolecules},
  volume    = {13},
  journal   = {Biomolecules},
  edition   = {1},
  publisher = {MDPI},
  address   = {Basel, Schweiz},
  issn      = {2218-273X},
  doi       = {10.3390/biom13010144},
  pages     = {1 -- 23},
  year      = {2023},
  abstract  = {Sulfur is an important element that is incorporated into many biomolecules in humans. The incorporation and transfer of sulfur into biomolecules is, however, facilitated by a series of different sulfurtransferases. Among these sulfurtransferases is the human mercaptopyruvate sulfurtransferase (MPST) also designated as tRNA thiouridine modification protein (TUM1). The role of the human TUM1 protein has been suggested in a wide range of physiological processes in the cell among which are but not limited to involvement in Molybdenum cofactor (Moco) biosynthesis, cytosolic tRNA thiolation and generation of H2S as signaling molecule both in mitochondria and the cytosol. Previous interaction studies showed that TUM1 interacts with the L-cysteine desulfurase NFS1 and the Molybdenum cofactor biosynthesis protein 3 (MOCS3). Here, we show the roles of TUM1 in human cells using CRISPR/Cas9 genetically modified Human Embryonic Kidney cells. Here, we show that TUM1 is involved in the sulfur transfer for Molybdenum cofactor synthesis and tRNA thiomodification by spectrophotometric measurement of the activity of sulfite oxidase and liquid chromatography quantification of the level of sulfur-modified tRNA. Further, we show that TUM1 has a role in hydrogen sulfide production and cellular bioenergetics.},
  language  = {en}
}
@article{GarridoLeimkuehler2021,
  author    = {Garrido, Claudia and Leimk{\"u}hler, Silke},
  title     = {The inactivation of human aldehyde oxidase 1 by hydrogen peroxide and superoxide},
  series = {Drug metabolism and disposition / American Society for Pharmacology and Experimental Therapeutics},
  volume    = {49},
  journal   = {Drug metabolism and disposition / American Society for Pharmacology and Experimental Therapeutics},
  number    = {9},
  publisher = {American Society for Pharmacology and Experimental Therapeutics},
  address   = {Bethesda},
  issn      = {1521-009X},
  doi       = {10.1124/dmd.121.000549},
  pages     = {729 -- 735},
  year      = {2021},
  abstract  = {Mammalian aldehyde oxidases (AOX) are molybdo-flavoenzymes of pharmacological and pathophysiologic relevance that are involved in phase I drug metabolism and, as a product of their enzymatic activity, are also involved in the generation of reactive oxygen species. So far, the physiologic role of aldehyde oxidase 1 in the human body remains unknown. The human enzyme hAOX1 is characterized by a broad substrate specificity, oxidizing aromatic/aliphatic aldehydes into their corresponding carboxylic acids, and hydroxylating various heteroaromatic rings. The enzyme uses oxygen as terminal electron acceptor to produce hydrogen peroxide and superoxide during turnover. Since hAOX1 and, in particular, some natural variants produce not only H2O2 but also high amounts of superoxide, we investigated the effect of both ROS molecules on the enzymatic activity of hAOX1 in more detail. We compared hAOX1 to the high-O-2(.-)-producing natural variant L438V for their time-dependent inactivation with H2O2/O-2(.-) during substrate turnover. We show that the inactivation of the hAOX1 wild-type enzyme is mainly based on the production of hydrogen peroxide, whereas for the variant L438V, both hydrogen peroxide and superoxide contribute to the time-dependent inactivation of the enzyme during turnover. Further, the level of inactivation was revealed to be substrate-dependent: using substrates with higher turnover numbers resulted in a faster inactivation of the enzymes. Analysis of the inactivation site of the enzyme identified a loss of the terminal sulfido ligand at the molybdenum active site by the produced ROS during turnover.},
  language  = {en}
}
@article{YildizLeimkuehler2021,
  author    = {Yildiz, Tugba and Leimk{\"u}hler, Silke},
  title     = {TusA is a versatile protein that links translation efficiency to cell division in Escherichia coli},
  series = {Journal of bacteriology},
  volume    = {203},
  journal   = {Journal of bacteriology},
  number    = {7},
  publisher = {American Society for Microbiology},
  address   = {Washington},
  issn      = {1098-5530},
  doi       = {10.1128/JB.00659-20},
  pages     = {20},
  year      = {2021},
  abstract  = {To enable accurate and efficient translation, sulfur modifications are introduced posttranscriptionally into nucleosides in tRNAs. The biosynthesis of tRNA sulfur modifications involves unique sulfur trafficking systems for the incorporation of sulfur atoms in different nucleosides of tRNA. One of the proteins that is involved in inserting the sulfur for 5-methylaminomethyl-2-thiouridine (mnm(5)s(2)U34) modifications in tRNAs is the TusA protein. TusA, however, is a versatile protein that is also involved in numerous other cellular pathways. Despite its role as a sulfur transfer protein for the 2-thiouridine formation in tRNA, a fundamental role of TusA in the general physiology of Escherichia coli has also been discovered. Poor viability, a defect in cell division, and a filamentous cell morphology have been described previously for tusA-deficient cells. In this report, we aimed to dissect the role of TusA for cell viability. We were able to show that the lack of the thiolation status of wobble uridine (U-34) nucleotides present on Lys, Gln, or Glu in tRNAs has a major consequence on the translation efficiency of proteins; among the affected targets are the proteins RpoS and Fis. Both proteins are major regulatory factors, and the deregulation of their abundance consequently has a major effect on the cellular regulatory network, with one consequence being a defect in cell division by regulating the FtsZ ring formation. <br /> IMPORTANCE More than 100 different modifications are found in RNAs. One of these modifications is the mnm(5)s(2)U modification at the wobble position 34 of tRNAs for Lys, Gln, and Glu. The functional significance of U34 modifications is substantial since it restricts the conformational flexibility of the anticodon, thus providing translational fidelity. We show that in an Escherichia coli TusA mutant strain, involved in sulfur transfer for the mnm(5)s(2)U34 thio modifications, the translation efficiency of RpoS and Fis, two major cellular regulatory proteins, is altered. Therefore, in addition to the transcriptional regulation and the factors that influence protein stability, tRNA modifications that ensure the translational efficiency provide an additional crucial regulatory factor for protein synthesis.},
  language  = {en}
}
@article{HasnatZupokOlasApeltetal.2021,
  author    = {Hasnat, Muhammad Abrar and Zupok, Arkadiusz and Olas-Apelt, Justyna Jadwiga and M{\"u}ller-R{\"o}ber, Bernd and Leimk{\"u}hler, Silke},
  title     = {A-type carrier proteins are involved in [4Fe-4S] cluster insertion into the radical S-adenosylmethionine protein MoaA for the synthesis of active molybdoenzymes},
  series = {Journal of bacteriology},
  volume    = {203},
  journal   = {Journal of bacteriology},
  number    = {12},
  publisher = {American Society for Microbiology},
  address   = {Washington},
  issn      = {1098-5530},
  doi       = {10.1128/JB.00086-21},
  pages     = {20},
  year      = {2021},
  abstract  = {Iron sulfur (Fe-S) clusters are important biological cofactors present in proteins with crucial biological functions, from photosynthesis to DNA repair, gene expression, and bioenergetic processes. For the insertion of Fe-S clusters into proteins, A-type carrier proteins have been identified. So far, three of them have been characterized in detail in Escherichia coli, namely, IscA, SufA, and ErpA, which were shown to partially replace each other in their roles in [4Fe-4S] cluster insertion into specific target proteins. To further expand the knowledge of [4Fe-4S] cluster insertion into proteins, we analyzed the complex Fe-S cluster-dependent network for the synthesis of the molybdenum cofactor (Moco) and the expression of genes encoding nitrate reductase in E. coli. Our studies include the identification of the A-type carrier proteins ErpA and IscA, involved in [4Fe-4S] cluster insertion into the radical Sadenosyl-methionine (SAM) enzyme MoaA. We show that ErpA and IscA can partially replace each other in their role to provide [4Fe-4S] clusters for MoaA. Since most genes expressing molybdoenzymes are regulated by the transcriptional regulator for fumarate and nitrate reduction (FNR) under anaerobic conditions, we also identified the proteins that are crucial to obtain an active FNR under conditions of nitrate respiration. We show that ErpA is essential for the FNR-dependent expression of the narGHJI operon, a role that cannot be compensated by IscA under the growth conditions tested. SufA does not appear to have a role in Fe-S cluster insertion into MoaA or FNR under anaerobic growth employing nitrate respiration, based on the low level of gene expression. <br /> IMPORTANCE Understanding the assembly of iron-sulfur (Fe-S) proteins is relevant to many fields, including nitrogen fixation, photosynthesis, bioenergetics, and gene regulation. Remaining critical gaps in our knowledge include how Fe-S clusters are transferred to their target proteins and how the specificity in this process is achieved, since different forms of Fe-S clusters need to be delivered to structurally highly diverse target proteins. Numerous Fe-S carrier proteins have been identified in prokaryotes like Escherichia coli, including ErpA, IscA, SufA, and NfuA. In addition, the diverse Fe-S cluster delivery proteins and their target proteins underlie a complex regulatory network of expression, to ensure that both proteins are synthesized under particular growth conditions.},
  language  = {en}
}
@misc{Leimkuehler2020,
  author    = {Leimk{\"u}hler, Silke},
  title     = {The biosynthesis of the molybdenum cofactors in Escherichia coli},
  series = {Environmental microbiology},
  volume    = {22},
  journal   = {Environmental microbiology},
  number    = {6},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {1462-2912},
  doi       = {10.1111/1462-2920.15003},
  pages     = {2007 -- 2026},
  year      = {2020},
  abstract  = {The biosynthesis of the molybdenum cofactor (Moco) is highly conserved among all kingdoms of life. In all molybdoenzymes containing Moco, the molybdenum atom is coordinated to a dithiolene group present in the pterin-based 6-alkyl side chain of molybdopterin (MPT). In general, the biosynthesis of Moco can be divided into four steps in in bacteria: (i) the starting point is the formation of the cyclic pyranopterin monophosphate (cPMP) from 5 '-GTP, (ii) in the second step the two sulfur atoms are inserted into cPMP leading to the formation of MPT, (iii) in the third step the molybdenum atom is inserted into MPT to form Moco and (iv) in the fourth step bis-Mo-MPT is formed and an additional modification of Moco is possible with the attachment of a nucleotide (CMP or GMP) to the phosphate group of MPT, forming the dinucleotide variants of Moco. This review presents an update on the well-characterized Moco biosynthesis in the model organism Escherichia coli including novel discoveries from the recent years.},
  language  = {en}
}
@article{NishinoOkamotoLeimkuehler2017,
  author    = {Nishino, Takeshi and Okamoto, Ken and Leimk{\"u}hler, Silke},
  title     = {Enzymes of the Xanthine Oxidase Family},
  series = {Molybdenum and tungsten enzymes : biochemistry},
  volume    = {5},
  journal   = {Molybdenum and tungsten enzymes : biochemistry},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  isbn      = {978-1-78262-391-5},
  doi       = {10.1039/9781782623915-00192},
  pages     = {192 -- 239},
  year      = {2017},
  abstract  = {Enzymes from the xanthine oxidase (XO) family of molybdenum enzymes are generally, with some exceptions, molybdenum iron-sulfur flavin hydroxylases. Mammalian xanthine oxidoreductase and aldehyde oxidase were among the first enzymes to be studied in detail more than 100 years ago and, surprisingly, they continue to be thoroughly studied in molecular detail with many open and unresolved questions remaining. Enzymes of the XO family are characterized by a molybdenum cofactor (Moco) active site with a MoVIOS(OH) ligand sphere where substrate hydroxylation of either aromatic or aliphatic carbon centers is catalyzed. During the reaction, electrons are transferred to the oxidizing substrate, most commonly O2 or NAD+, which react at the FAD site.},
  language  = {en}
}
@article{LeimkuehlerLemaireIobbiNivol2017,
  author    = {Leimk{\"u}hler, Silke and Lemaire, Olivier N. and Iobbi-Nivol, Chantal},
  title     = {Bacterial Molybdoenzymes},
  series = {Molybdenum and tungsten enzymes : biochemistry},
  volume    = {5},
  journal   = {Molybdenum and tungsten enzymes : biochemistry},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  isbn      = {978-1-78262-391-5},
  doi       = {10.1039/9781782623915-00117},
  pages     = {117 -- 142},
  year      = {2017},
  abstract  = {The biogenesis of molybdoenzymes is a cytoplasmic event requiring both the folded apoenzymes and the matured molybdenum cofactor. The structure and the complexity of the molybdenum cofactor varies in each molybdoenzyme family and consequently different accessory proteins are required for the maturation of the respective enzymes. Thus, for enzymes of both the DMSO reductase and xanthine oxidase families, specific chaperones exist which are dedicated to increase the stability and the folding of specific members of each family. In this review, we describe the role of these chaperones for molybdoenzyme maturation. We present a model which describes step by step the mechanism of the maturation of representative molybdoenzymes from each family.},
  language  = {en}
}
@article{LeimkuehlerMendel2017,
  author    = {Leimk{\"u}hler, Silke and Mendel, Ralf-Rainer},
  title     = {Molybdenum Cofactor Biosynthesis},
  series = {Molybdenum and tungsten enzymes: biochemistry},
  volume    = {5},
  journal   = {Molybdenum and tungsten enzymes: biochemistry},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  isbn      = {978-1-78262-391-5},
  doi       = {10.1039/9781782623915},
  pages     = {100 -- 116},
  year      = {2017},
  abstract  = {The biosynthesis of the molybdenum cofactor (Moco) is highly conserved among all kingdoms of life. In all molybdoenzymes with the exception of nitrogenase, the molybdenum atom is coordinated to a dithiolene group present in the pterin-based 6-alkyl side chain of molybdopterin (MPT). In general, the biosynthesis of Moco can be divided into three steps in eukaryotes, and four steps in bacteria and archaea: (i) the starting point is the formation of the cyclic pyranopterin monophosphate (cPMP) from 5′GTP, (ii) in the second step the two sulfur molecules are inserted into cPMP leading to the formation of MPT, (iii) in the third step the molybdenum atom is inserted into molybdopterin to form Moco and (iv) additional modification of Moco occurs in bacteria and archaea with the attachment of a nucleotide (CMP or GMP) to the phosphate group of MPT, forming the dinucleotide variants of Moco. This review will focus on the biosynthesis of Moco in bacteria, humans and plants.},
  language  = {en}
}
@misc{TiedemannIobbiNivolLeimkuehler2022,
  author    = {Tiedemann, Kim and Iobbi-Nivol, Chantal and Leimk{\"u}hler, Silke},
  title     = {The Role of the Nucleotides in the Insertion of the bis-Molybdopterin Guanine Dinucleotide Cofactor into apo-Molybdoenzymes},
  series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  publisher = {Universit{\"a}tsverlag Potsdam},
  address   = {Potsdam},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-56172},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-561728},
  pages     = {1 -- 15},
  year      = {2022},
  abstract  = {The role of the GMP nucleotides of the bis-molybdopterin guanine dinucleotide (bis-MGD) cofactor of the DMSO reductase family has long been a subject of discussion. The recent characterization of the bis-molybdopterin (bis-Mo-MPT) cofactor present in the E. coli YdhV protein, which differs from bis-MGD solely by the absence of the nucleotides, now enables studying the role of the nucleotides of bis-MGD and bis-MPT cofactors in Moco insertion and the activity of molybdoenzymes in direct comparison. Using the well-known E. coli TMAO reductase TorA as a model enzyme for cofactor insertion, we were able to show that the GMP nucleotides of bis-MGD are crucial for the insertion of the bis-MGD cofactor into apo-TorA.},
  language  = {en}
}
@article{TiedemannIobbiNivolLeimkuehler2022,
  author    = {Tiedemann, Kim and Iobbi-Nivol, Chantal and Leimk{\"u}hler, Silke},
  title     = {The Role of the Nucleotides in the Insertion of the bis-Molybdopterin Guanine Dinucleotide Cofactor into apo-Molybdoenzymes},
  series = {Molecules},
  volume    = {27},
  journal   = {Molecules},
  edition   = {9},
  publisher = {MDPI},
  address   = {Basel, Schweiz},
  issn      = {1420-3049},
  doi       = {10.3390/molecules27092993},
  pages     = {1 -- 15},
  year      = {2022},
  abstract  = {The role of the GMP nucleotides of the bis-molybdopterin guanine dinucleotide (bis-MGD) cofactor of the DMSO reductase family has long been a subject of discussion. The recent characterization of the bis-molybdopterin (bis-Mo-MPT) cofactor present in the E. coli YdhV protein, which differs from bis-MGD solely by the absence of the nucleotides, now enables studying the role of the nucleotides of bis-MGD and bis-MPT cofactors in Moco insertion and the activity of molybdoenzymes in direct comparison. Using the well-known E. coli TMAO reductase TorA as a model enzyme for cofactor insertion, we were able to show that the GMP nucleotides of bis-MGD are crucial for the insertion of the bis-MGD cofactor into apo-TorA.},
  language  = {en}
}
@misc{LeimkuehlerBuehningBeilschmidt2017,
  author    = {Leimk{\"u}hler, Silke and B{\"u}hning, Martin and Beilschmidt, Lena},
  title     = {Shared sulfur mobilization routes for tRNA thiolation and molybdenum cofactor biosynthesis in prokaryotes and eukaryotes},
  series = {Biomolecules},
  volume    = {7},
  journal   = {Biomolecules},
  number    = {1},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2218-273X},
  doi       = {10.3390/biom7010005},
  pages     = {20},
  year      = {2017},
  abstract  = {Modifications of transfer RNA (tRNA) have been shown to play critical roles in the biogenesis, metabolism, structural stability and function of RNA molecules, and the specific modifications of nucleobases with sulfur atoms in tRNA are present in pro- and eukaryotes. Here, especially the thiomodifications xm(5)s(2)U at the wobble position 34 in tRNAs for Lys, Gln and Glu, were suggested to have an important role during the translation process by ensuring accurate deciphering of the genetic code and by stabilization of the tRNA structure. The trafficking and delivery of sulfur nucleosides is a complex process carried out by sulfur relay systems involving numerous proteins, which not only deliver sulfur to the specific tRNAs but also to other sulfur-containing molecules including iron-sulfur clusters, thiamin, biotin, lipoic acid and molybdopterin (MPT). Among the biosynthesis of these sulfur-containing molecules, the biosynthesis of the molybdenum cofactor (Moco) and the synthesis of thio-modified tRNAs in particular show a surprising link by sharing protein components for sulfur mobilization in pro- and eukaryotes.},
  language  = {en}
}
@article{FriemelMareljaLietal.2017,
  author    = {Friemel, Martin and Marelja, Zvonimir and Li, Kuanyu and Leimk{\"u}hler, Silke},
  title     = {The N-Terminus of Iron-Sulfur Cluster Assembly Factor ISD11 Is Crucial for Subcellular Targeting and Interaction with L-Cysteine Desulfurase NFS1},
  series = {Biochemistry},
  volume    = {56},
  journal   = {Biochemistry},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0006-2960},
  doi       = {10.1021/acs.biochem.6b01239},
  pages     = {1797 -- 1808},
  year      = {2017},
  abstract  = {Assembly of iron sulfur (FeS) clusters is an important process in living cells. The initial sulfur mobilization step for FeS cluster biosynthesis is catalyzed by L-cysteine desulfurase NFS1, a reaction that is localized in mitochondria in humans. In humans, the function of NFS1 depends on the ISD11 protein, which is required to stabilize its structure. The NFS1/ISD11 complex further interacts with scaffold protein ISCU and regulator protein frataxin, thereby forming a quaternary complex for FeS cluster formation. It has been suggested that the role of ISD11 is not restricted to its role in stabilizing the structure of NFS1, because studies of single-amino acid variants of ISD11 additionally demonstrated its importance for the correct assembly of the quaternary complex. In this study, we are focusing on the N-terminal region of ISD11 to determine the role of N-terminal amino acids in the formation of the complex with NFS1 and to reveal the mitochondria) targeting sequence for subcellular localization. Our in vitro studies with the purified proteins and in vivo studies in a cellular system show that the first 10 N-terminal amino acids of ISD11 are indispensable for the activity of NFS1 and especially the conserved "LYR" motif is essential for the role of ISD11 in forming a stable and active complex with NFS1.},
  language  = {en}
}
@misc{RomaoCoelhoSantosSilvaetal.2017,
  author    = {Romao, Maria Joao and Coelho, Catarina and Santos-Silva, Teresa and Foti, Alessandro and Terao, Mineko and Garattini, Enrico and Leimk{\"u}hler, Silke},
  title     = {Structural basis for the role of mammalian aldehyde oxidases in the metabolism of drugs and xenobiotics},
  series = {Current Opinion in Chemical Biology},
  volume    = {37},
  journal   = {Current Opinion in Chemical Biology},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {1367-5931},
  doi       = {10.1016/j.cbpa.2017.01.005},
  pages     = {39 -- 47},
  year      = {2017},
  abstract  = {Aldehyde oxidases (AOXs) are molybdo-flavoenzymes characterized by broad substrate specificity, oxidizing aromatic/aliphatic aldehydes into the corresponding carboxylic acids and hydroxylating various heteroaromatic rings. Mammals are characterized by a complement of species specific AOX isoenzymes, that varies from one in humans (AOX1) to four in rodents (AOX1, AOX2, AOX3 and AOX4). The physiological function of mammalian AOX isoenzymes is unknown, although human AOX1 is an emerging enzyme in phase-I drug metabolism. Indeed, the number of therapeutic molecules under development which act as AOX substrates is increasing. The recent crystallization and structure determination of human AOX1 as well as mouse AOX3 has brought new insights into the mechanisms underlying substrate/inhibitor binding as well as the catalytic activity of this class of enzymes.},
  language  = {en}
}
@article{BuehningVallerianiLeimkuehler2017,
  author    = {B{\"u}hning, Martin and Valleriani, Angelo and Leimk{\"u}hler, Silke},
  title     = {The role of SufS is restricted to Fe-S cluster biosynthesis in escherichia coli},
  series = {Biochemistry},
  volume    = {56},
  journal   = {Biochemistry},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0006-2960},
  doi       = {10.1021/acs.biochem.7b00040},
  pages     = {1987 -- 2000},
  year      = {2017},
  abstract  = {In Escherichia coli, two different systems that are important for the coordinate formation of Fe-S clusters have been identified, namely, the ISC and SUF systems. The ISC system is the housekeeping Fe-S machinery, which provides Fe-S clusters for numerous cellular proteins. The IscS protein of this system was additionally revealed to be the primary sulfur donor for several sulfur-containing molecules with important biological functions, among which are the molybdenum cofactor (Moco) and thiolated nucleosides in tRNA. Here, we show that deletion of central components of the ISC system in addition to IscS leads to an overall decrease in Fe-S cluster enzyme and molybdoenzyme activity in addition to a decrease in the number of Fe-S-dependent thiomodifications of tRNA, based on the fact that some proteins involved in Moco biosynthesis and tRNA thiolation are Fe-S-dependent. Complementation of the ISC deficient strains with the suf operon restored the activity of Fe-S-containing proteins, including the MoaA protein, which is involved in the conversion of 5′GTP to cyclic pyranopterin monophosphate in the fist step of Moco biosynthesis. While both systems share a high degree of similarity, we show that the function of their respective l-cysteine desulfurase IscS or SufS is specific for each cellular pathway. It is revealed that SufS cannot play the role of IscS in sulfur transfer for the formation of 2-thiouridine, 4-thiouridine, or the dithiolene group of molybdopterin, being unable to interact with TusA or ThiI. The results demonstrate that the role of the SUF system is exclusively restricted to Fe-S cluster assembly in the cell.},
  language  = {en}
}
@article{ParagasHumphreysMinetal.2017,
  author    = {Paragas, Erickson M. and Humphreys, Sara C. and Min, Joshua and Joswig-Jones, Carolyn A. and Leimk{\"u}hler, Silke and Jones, Jeffrey P.},
  title     = {ecoAO},
  series = {ACS OMEGA},
  volume    = {2},
  journal   = {ACS OMEGA},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {2470-1343},
  doi       = {10.1021/acsomega.7b01054},
  pages     = {4820 -- 4827},
  year      = {2017},
  abstract  = {Although aldehyde oxidase (AO) is an important hepatic drug-metabolizing enzyme, it remains understudied and is consequently often overlooked in preclinical studies, an oversight that has resulted in the failure of multiple clinical trials. AO's preclusion to investigation stems from the following: (1) difficulties synthesizing metabolic standards due to the chemospecificity and regiospecificity of the enzyme and (2) significant inherent variability across existing in vitro systems including liver cytosol, S9 fractions, and primary hepatocytes, which lack specificity and generate discordant expression and activity profiles. Here, we describe a practical bacterial biotransformation system, ecoAO, addressing both issues simultaneously. ecoAO is a cell paste of MoCo-producing Escherichia coli strain TP1017 expressing human AO. It exhibits specific activity toward known substrates, zoniporide, 4-trans-(N,N-dimethylamino)cinnamaldehyde, O6-benzylguanine, and zaleplon; it also has utility as a biocatalyst, yielding milligram quantities of synthetically challenging metabolite standards such as 2-oxo-zoniporide. Moreover, ecoAO enables routine determination of kcat and V/K, which are essential parameters for accurate in vivo clearance predictions. Furthermore, ecoAO has potential as a preclinical in vitro screening tool for AO activity, as demonstrated by its metabolism of 3-aminoquinoline, a previously uncharacterized substrate. ecoAO promises to provide easy access to metabolites with the potential to improve pharmacokinetic clearance predictions and guide drug development.},
  language  = {en}
}
@article{KuecuekgoezeLeimkuehler2018,
  author    = {K{\"u}{\c{c}}{\"u}kg{\"o}ze, G{\"o}khan and Leimk{\"u}hler, Silke},
  title     = {Direct comparison of the four aldehyde oxidase enzymes present in mouse gives insight into their substrate specificities},
  series = {PLOS ONE},
  volume    = {13},
  journal   = {PLOS ONE},
  number    = {1},
  publisher = {Public Library of Science},
  address   = {San Fransisco},
  issn      = {1932-6203},
  doi       = {10.1371/journal.pone.0191819},
  pages     = {20},
  year      = {2018},
  abstract  = {Mammalian aldehyde oxidases (AOXs) are molybdo-flavoenzymes which are present in many tissues in various mammalian species, including humans and rodents. Different species contain a different number of AOX isoforms. In particular, the reasons why mammals other than humans express a multiplicity of tissue-specific AOX enzymes is unknown. In mouse, the isoforms mAOX1, mAOX3, mAOX4 and mAOX2 are present. We previously established a codon-optimized heterologous expression systems for the mAOX1-4 isoforms in Escherichia coli that gives yield to sufficient amounts of active protein for kinetic characterizations and sets the basis in this study for site-directed mutagenesis and structure-function studies. A direct and simultaneous comparison of the enzymatic properties and characteristics of the four enzymes on a larger number of substrates has never been performed. Here, thirty different structurally related aromatic, aliphatic and N-heterocyclic compounds were used as substrates, and the kinetic parameters of all four mAOX enzymes were directly compared. The results show that especially mAOX4 displays a higher substrate selectivity, while no major differences between mAOX1, mAOX2 and mAOX3 were identified. Generally, mAOX1 was the enzyme with the highest catalytic turnover for most substrates. To understand the factors that contribute to the substrate specificity of mAOX4, site-directed mutagenesis was applied to substitute amino acids in the substrate-binding funnel by the ones present in mAOX1, mAOX3, and mAOX2. An increase in activity was obtained by the amino acid exchange M1088V in the active site identified to be specific for mAOX4, to the amino acid identified in mAOX3.},
  language  = {en}
}
@article{KaufmannDuffusMitrovaetal.2018,
  author    = {Kaufmann, Hans Paul and Duffus, Benjamin R. and Mitrova, Biljana and Iobbi-Nivol, Chantal and Teutloff, Christian and Nimtz, Manfred and Jaensch, Lothar and Wollenberger, Ulla and Leimk{\"u}hler, Silke},
  title     = {Modulating the Molybdenum Coordination Sphere of Escherichia coli Trimethylamie N-Oxide Reductase},
  series = {Biochemistry},
  volume    = {57},
  journal   = {Biochemistry},
  number    = {7},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0006-2960},
  doi       = {10.1021/acs.biochem.7b01108},
  pages     = {1130 -- 1143},
  year      = {2018},
  abstract  = {The well-studied enterobacterium Escherichia coli present in the human gut can reduce trimethylamine N-oxide (TMAO) to trimethylamine during anaerobic respiration. The TMAO reductase TorA is a monomeric, bis-molybdopterin guanine dinucleotide (bis-MGD) cofactor-containing enzyme that belongs to the dimethyl sulfoxide reductase family of molybdoenzymes. We report on a system for the in vitro reconstitution of TorA with molybdenum cofactors (Moco) from different sources. Higher TMAO reductase activities for TorA were obtained when using Moco sources containing a sulfido ligand at the molybdenum atom. For the first time, we were able to isolate functional bis-MGD from Rhodobacter capsulatus formate dehydrogenase (FDH), which remained intact in its isolated state and after insertion into apo-TorA yielded a highly active enzyme. Combined characterizations of the reconstituted TorA enzymes by electron paramagnetic resonance spectroscopy and direct electrochemistry emphasize that TorA activity can be modified by changes in the Mo coordination sphere. The combination of these results together with studies of amino acid exchanges at the active site led us to propose a novel model for binding of the substrate to the molybdenum atom of TorA.},
  language  = {en}
}
@article{KaufmannDuffusTeutloffetal.2018,
  author    = {Kaufmann, Paul and Duffus, Benjamin R. and Teutloff, Christian and Leimk{\"u}hler, Silke},
  title     = {Functional Studies on Oligotropha carboxidovorans Molybdenum-Copper CO Dehydrogenase Produced in Escherichia coli},
  series = {Biochemistry},
  volume    = {57},
  journal   = {Biochemistry},
  number    = {19},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0006-2960},
  doi       = {10.1021/acs.biochem.8b00128},
  pages     = {2889 -- 2901},
  year      = {2018},
  abstract  = {The Mo/Cu-dependent CO dehydrogenase (CODH) from Oligotropha carboxidovorans is an enzyme that is able to catalyze both the oxidation of CO to CO2 and the oxidation of H-2 to protons and electrons. Despite the close to atomic resolution structure (1.1 angstrom), significant uncertainties have remained with regard to the reaction mechanism of substrate oxidation at the unique Mo/Cu center, as well as the nature of intermediates formed during the catalytic cycle. So far, the investigation of the role of amino acids at the active site was hampered by the lack of a suitable expression system that allowed for detailed site-directed mutagenesis studies at the active site. Here, we report on the establishment of a functional heterologous expression system of O. carboxidovorans CODH in Escherichia coli. We characterize the purified enzyme in detail by a combination of kinetic and spectroscopic studies and show that it was purified in a form with characteristics comparable to those of the native enzyme purified from O. carboxidovorans. With this expression system in hand, we were for the first time able to generate active-site variants of this enzyme. Our work presents the basis for more detailed studies of the reaction mechanism for CO and H-2 oxidation of Mo/Cu-dependent CODHs in the future.},
  language  = {en}
}
@article{OttoMareljaSchoofsetal.2018,
  author    = {Otto, Nils and Marelja, Zvonimir and Schoofs, Andreas and Kranenburg, Holger and Bittern, Jonas and Yildirim, Kerem and Berh, Dimitri and Bethke, Maria and Thomas, Silke and Rode, Sandra and Risse, Benjamin and Jiang, Xiaoyi and Pankratz, Michael and Leimk{\"u}hler, Silke and Kl{\"a}mbt, Christian},
  title     = {The sulfite oxidase Shopper controls neuronal activity by regulating glutamate homeostasis in Drosophila ensheathing glia},
  series = {Nature Communications},
  volume    = {9},
  journal   = {Nature Communications},
  publisher = {Nature Publ. Group},
  address   = {London},
  issn      = {2041-1723},
  doi       = {10.1038/s41467-018-05645-z},
  pages     = {12},
  year      = {2018},
  abstract  = {Specialized glial subtypes provide support to developing and functioning neural networks. Astrocytes modulate information processing by neurotransmitter recycling and release of neuromodulatory substances, whereas ensheathing glial cells have not been associated with neuromodulatory functions yet. To decipher a possible role of ensheathing glia in neuronal information processing, we screened for glial genes required in the Drosophila central nervous system for normal locomotor behavior. Shopper encodes a mitochondrial sulfite oxidase that is specifically required in ensheathing glia to regulate head bending and peristalsis. shopper mutants show elevated sulfite levels affecting the glutamate homeostasis which then act on neuronal network function. Interestingly, human patients lacking the Shopper homolog SUOX develop neurological symptoms, including seizures. Given an enhanced expression of SUOX by oligodendrocytes, our findings might indicate that in both invertebrates and vertebrates more than one glial cell type may be involved in modulating neuronal activity.},
  language  = {en}
}
@article{SchwanholdIobbiNivolLehmannetal.2018,
  author    = {Schwanhold, Nadine and Iobbi-Nivol, Chantal and Lehmann, Angelika and Leimk{\"u}hler, Silke},
  title     = {Same but different},
  series = {PLoS one},
  volume    = {13},
  journal   = {PLoS one},
  number    = {11},
  publisher = {PLoS},
  address   = {San Fransisco},
  issn      = {1932-6203},
  doi       = {10.1371/journal.pone.0201935},
  pages     = {24},
  year      = {2018},
  abstract  = {The maturation of bacterial molybdoenzymes is a complex process leading to the insertion of the bulky bis-molybdopterin guanine dinucleotide (bis-MGD) cofactor into the apoenzyme. Most molybdoenzymes were shown to contain a specific chaperone for the insertion of the bis-MGD cofactor. Formate dehydrogenases (FDH) together with their molecular chaperone partner seem to display an exception to this specificity rule, since the chaperone FdhD has been proven to be involved in the maturation of all three FDH enzymes present in Escherichia colt. Multiple roles have been suggested for FdhD-like chaperones in the past, including the involvement in a sulfur transfer reaction from the L-cysteine desulfurase IscS to bis-MGD by the action of two cysteine residues present in a conserved CXXC motif of the chaperones. However, in this study we show by phylogenetic analyses that the CXXC motif is not conserved among FdhD-like chaperones. We compared in detail the FdhD-like homologues from Rhodobacter capsulatus and E. colt and show that their roles in the maturation of FDH enzymes from different subgroups can be exchanged. We reveal that bis-MGDbinding is a common characteristic of FdhD-like proteins and that the cofactor is bound with a sulfido-ligand at the molybdenum atom to the chaperone. Generally, we reveal that the cysteine residues in the motif CXXC of the chaperone are not essential for the production of active FDH enzymes.},
  language  = {en}
}
@article{BurschelDecovicNuberetal.2018,
  author    = {Burschel, Sabrina and Decovic, Doris Kreuzer and Nuber, Franziska and Stiller, Marie and Hofmann, Maud and Zupok, Arkadiusz and Siemiatkowska, Beata and Gorka, Michal Jakub and Leimk{\"u}hler, Silke and Friedrich, Thorsten},
  title     = {Iron-sulfur cluster carrier proteins involved in the assembly of Escherichia coli NADH},
  series = {Molecular microbiology},
  volume    = {111},
  journal   = {Molecular microbiology},
  number    = {1},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0950-382X},
  doi       = {10.1111/mmi.14137},
  pages     = {31 -- 45},
  year      = {2018},
  abstract  = {The NADH:ubiquinone oxidoreductase (respiratory complex I) is the main entry point for electrons into the Escherichia coli aerobic respiratory chain. With its sophisticated setup of 13 different subunits and 10 cofactors, it is anticipated that various chaperones are needed for its proper maturation. However, very little is known about the assembly of E. coli complex I, especially concerning the incorporation of the iron-sulfur clusters. To identify iron-sulfur cluster carrier proteins possibly involved in the process, we generated knockout strains of NfuA, BolA, YajL, Mrp, GrxD and IbaG that have been reported either to be involved in the maturation of mitochondrial complex I or to exert influence on the clusters of bacterial complex. We determined the NADH and succinate oxidase activities of membranes from the mutant strains to monitor the specificity of the individual mutations for complex I. The deletion of NfuA, BolA and Mrp led to a decreased stability and partially disturbed assembly of the complex as determined by sucrose gradient centrifugation and native PAGE. EPR spectroscopy of cytoplasmic membranes revealed that the BolA deletion results in the loss of the binuclear Fe/S cluster N1b.},
  language  = {en}
}
@article{TanabeLeimkuehlerDahl2019,
  author    = {Tanabe, Tomohisa Sebastian and Leimk{\"u}hler, Silke and Dahl, Christiane},
  title     = {The functional diversity of the prokaryotic sulfur carrier protein TusA},
  series = {Advances in microbial physiology},
  volume    = {75},
  journal   = {Advances in microbial physiology},
  editor    = {Poole, RK},
  publisher = {Elsevier Acad. Press},
  address   = {Amsterdam},
  isbn      = {978-0-12-817715-0},
  issn      = {0065-2911},
  doi       = {10.1016/bs.ampbs.2019.07.004},
  pages     = {233 -- 277},
  year      = {2019},
  abstract  = {Persulfide groups participate in a wide array of biochemical pathways and are chemically very versatile. The TusA protein has been identified as a central element supplying and transferring sulfur as persulfide to a number of important biosynthetic pathways, like molybdenum cofactor biosynthesis or thiomodifications in nucleosides of tRNAs. In recent years, it has furthermore become obvious that this protein is indispensable for the oxidation of sulfur compounds in the cytoplasm. Phylogenetic analyses revealed that different TusA protein variants exists in certain organisms, that have evolved to pursue specific roles in cellular pathways. The specific TusA-like proteins thereby cannot replace each other in their specific roles and are rather specific to one sulfur transfer pathway or shared between two pathways. While certain bacteria like Escherichia coli contain several copies of TusA-like proteins, in other bacteria like Allochromatium vinosum a single copy of TusA is present with an essential role for this organism. Here, we give an overview on the multiple roles of the various TusA-like proteins in sulfur transfer pathways in different organisms to shed light on the remaining mysteries of this versatile protein.},
  language  = {en}
}
@inproceedings{DuffusHartmannTeutloffetal.2019,
  author    = {Duffus, Benjamin R. and Hartmann, Tobias and Teutloff, Christian and Leimk{\"u}hler, Silke},
  title     = {Refining catalytic insights toward the chemical mechanism of R. capsulatus formate dehydrogenase via EPR spectroscopy},
  series = {Abstracts of papers : joint conference / The Chemical Institute of Cananda, CIC, American Chemical Society, ACS},
  volume    = {257},
  booktitle = {Abstracts of papers : joint conference / The Chemical Institute of Cananda, CIC, American Chemical Society, ACS},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0065-7727},
  pages     = {1},
  year      = {2019},
  language  = {en}
}
@article{MitrovaTadjoungWaffoKaufmannetal.2018,
  author    = {Mitrova, Biljana and Tadjoung Waffo, Armel Franklin and Kaufmann, Paul and Iobbi-Nivol, Chantal and Leimk{\"u}hler, Silke and Wollenberger, Ulla},
  title     = {Trimethylamine N-Oxide Electrochemical Biosensor with a Chimeric Enzyme},
  series = {ChemElectroChem},
  volume    = {6},
  journal   = {ChemElectroChem},
  number    = {6},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {2196-0216},
  doi       = {10.1002/celc.201801422},
  pages     = {1732 -- 1737},
  year      = {2018},
  abstract  = {For the first time, an enzyme-based electrochemical biosensor system for determination of trimethylamine N-oxide (TMAO) is described. It employs an active chimeric variant of TorA in combination with an enzymatically deoxygenating system and a low-potential mediator for effective regeneration of the enzyme and cathodic current generation. TMAO reductase (TorA) is a molybdoenzyme found in marine and most enterobacteria that specifically catalyzes the reduction of TMAO to trimethylamine (TMA). The chimeric TorA, named TorA-FDH, corresponds to the apoform of TorA from Escherichia coli reconstituted with the molybdenum cofactor from formate dehydrogenase (FDH). Each enzyme, TorA and TorA-FDH, was immobilized on the surface of a carbon electrode and protected with a dialysis membrane. The biosensor operates at an applied potential of -0.8V [vs. Ag/AgCl (1M KCl)] under ambient air conditions thanks to an additional enzymatic O-2-scavenger system. A comparison between the two enzymatic sensors revealed a much higher sensitivity for the biosensor with immobilized TorA-FDH. This biosensor exhibits a sensitivity of 14.16nA/M TMAO in a useful measuring range of 2-110M with a detection limit of LOD=2.96nM (S/N=3), and was similar for TMAO in buffer and in spiked serum samples. With a response time of 16 +/- 2 s, the biosensor is stable over prolonged daily measurements (n=20). This electrochemical biosensor provides suitable applications in detecting TMAO levels in human serum.},
  language  = {en}
}
@article{NeukranzKotterBeilschmidtetal.2019,
  author    = {Neukranz, Yannika and Kotter, Annika and Beilschmidt, Lena and Marelja, Zvonimir and Helm, Mark and Graf, Ralph and Leimk{\"u}hler, Silke},
  title     = {Analysis of the Cellular Roles of MOCS3 Identifies a MOCS3-Independent Localization of NFS1 at the Tips of the Centrosome},
  series = {Biochemistry},
  volume    = {58},
  journal   = {Biochemistry},
  number    = {13},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0006-2960},
  doi       = {10.1021/acs.biochem.8b01160},
  pages     = {1786 -- 1798},
  year      = {2019},
  abstract  = {The deficiency of the molybdenum cofactor (Moco) is an autosomal recessive disease, which leads to the loss of activity of all molybdoenzymes in humans with sulfite oxidase being the essential protein. Moco deficiency generally results in death in early childhood. Moco is a sulfur-containing cofactor synthesized in the cytosol with the sulfur being provided by a sulfur relay system composed of the L-cysteine desulfurase NFS1, MOCS3, and MOCS2A. Human MOCS3 is a dual-function protein that was shown to play an important role in Moco biosynthesis and in the mcm(5)s(2) U thio modifications of nucleosides in cytosolic tRNAs for Lys, Gln, and Glu. In this study, we constructed a homozygous MOCS3 knockout in HEK293T cells using the CRISPR/Cas9 system. The effects caused by the absence of MOCS3 were analyzed in detail. We show that sulfite oxidase activity was almost completely abolished, on the basis of the absence of Moco in these cells. In addition, mcm(5)s(2)U thio-modified tRNAs were not detectable. Because the L-cysteine desulfurase NFS1 was shown to act as a sulfur donor for MOCS3 in the cytosol, we additionally investigated the impact of a MOCS3 knockout on the cellular localization of NFS1. By different methods, we identified a MOCS3-independent novel localization of NFS1 at the centrosome.},
  language  = {en}
}
@article{ReschkeDuffusSchrapersetal.2019,
  author    = {Reschke, Stefan and Duffus, Benjamin R. and Schrapers, Peer and Mebs, Stefan and Teutloff, Christian and Dau, Holger and Haumann, Michael and Leimk{\"u}hler, Silke},
  title     = {Identification of YdhV as the First Molybdoenzyme Binding a Bis-Mo-MPT Cofactor in Escherichia coli},
  series = {Biochemistry},
  volume    = {58},
  journal   = {Biochemistry},
  number    = {17},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0006-2960},
  doi       = {10.1021/acs.biochem.9b00078},
  pages     = {2228 -- 2242},
  year      = {2019},
  abstract  = {The oxidoreductase YdhV in Escherichia coli has been predicted to belong to the family of molybdenum/tungsten cofactor (Moco/Wco)-containing enzymes. In this study, we characterized the YdhV protein in detail, which shares amino acid sequence homology with a tungsten-containing benzoyl-CoA reductase binding the bis-W-MPT (for metal-binding pterin) cofactor. The cofactor was identified to be of a bis-Mo-MPT type with no guanine nucleotides present, which represents a form of Moco that has not been found previously in any molybdoenzyme. Our studies showed that YdhV has a preference for bis-Mo-MPT over bis-W-MPT to be inserted into the enzyme. In-depth characterization of YdhV by X-ray absorption and electron paramagnetic resonance spectroscopies revealed that the bis-Mo-MPT cofactor in YdhV is redox active. The bis-Mo-MPT and bis-W-MPT cofactors include metal centers that bind the four sulfurs from the two dithiolene groups in addition to a cysteine and likely a sulfido ligand. The unexpected presence of a bis-Mo-MPT cofactor opens an additional route for cofactor biosynthesis in E. coli and expands the canon of the structurally highly versatile molybdenum and tungsten cofactors.},
  language  = {en}
}
@article{MotaEsmaeeliMoghaddamTabalvandaniCoelhoetal.2019,
  author    = {Mota, Cristiano and Esmaeeli Moghaddam Tabalvandani, Mariam and Coelho, Catarina and Santos-Silva, Teresa and Wolff, Martin and Foti, Alessandro and Leimk{\"u}hler, Silke and Romao, Maria Joao},
  title     = {Human aldehyde oxidase (hAOX1)},
  series = {FEBS Open Bio},
  volume    = {9},
  journal   = {FEBS Open Bio},
  number    = {5},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {2211-5463},
  doi       = {10.1002/2211-5463.12617},
  pages     = {925 -- 934},
  year      = {2019},
  abstract  = {Human aldehyde oxidase (hAOX1) is a molybdenum enzyme with high toxicological importance, but its physiological role is still unknown. hAOX1 metabolizes different classes of xenobiotics and is one of the main drug-metabolizing enzymes in the liver, along with cytochrome P450. hAOX1 oxidizes and inactivates a large number of drug molecules and has been responsible for the failure of several phase I clinical trials. The interindividual variability of drug-metabolizing enzymes caused by single nucleotide polymorphisms (SNPs) is highly relevant in pharmaceutical treatments. In this study, we present the crystal structure of the inactive variant G1269R, revealing the first structure of a molybdenum cofactor (Moco)-free form of hAOX1. These data allowed to model, for the first time, the flexible Gate 1 that controls access to the active site. Furthermore, we inspected the thermostability of wild-type hAOX1 and hAOX1 with various SNPs (L438V, R1231H, G1269R or S1271L) by CD spectroscopy and ThermoFAD, revealing that amino acid exchanges close to the Moco site can impact protein stability up to 10 degrees C. These results correlated with biochemical and structural data and enhance our understanding of hAOX1 and the effect of SNPs in the gene encoding this enzyme in the human population. EnzymesAldehyde oxidase (); xanthine dehydrogenase (); xanthine oxidase (). DatabasesStructural data are available in the Protein Data Bank under the accession number .},
  language  = {en}
}
@article{BadalyanDierichStibaetal.2014,
  author    = {Badalyan, Artavazd and Dierich, Marlen and Stiba, Konstanze and Schwuchow, Viola and Leimk{\"u}hler, Silke and Wollenberger, Ulla},
  title     = {Electrical wiring of the aldehyde oxidoreductase PaoABC with a polymer containing osmium redox centers},
  series = {Biosensors},
  volume    = {4},
  journal   = {Biosensors},
  number    = {4},
  publisher = {MDPI},
  address   = {Basel},
  doi       = {10.3390/bios4040403},
  pages     = {403 -- 421},
  year      = {2014},
  abstract  = {Biosensors for the detection of benzaldehyde and g-aminobutyric acid (GABA) are reported using aldehyde oxidoreductase PaoABC from Escherichia coli immobilized in a polymer containing bound low potential osmium redox complexes. The electrically connected enzyme already electrooxidizes benzaldehyde at potentials below -0.15 V (vs. Ag|AgCl, 1 M KCl). The pH-dependence of benzaldehyde oxidation can be strongly influenced by the ionic strength. The effect is similar with the soluble osmium redox complex and therefore indicates a clear electrostatic effect on the bioelectrocatalytic efficiency of PaoABC in the osmium containing redox polymer. At lower ionic strength, the pH-optimum is high and can be switched to low pH-values at high ionic strength. This offers biosensing at high and low pH-values. A "reagentless" biosensor has been formed with enzyme wired onto a screen-printed electrode in a flow cell device. The response time to addition of benzaldehyde is 30 s, and the measuring range is between 10-150 µM and the detection limit of 5 µM (signal to noise ratio 3:1) of benzaldehyde. The relative standard deviation in a series (n = 13) for 200 µM benzaldehyde is 1.9\%. For the biosensor, a response to succinic semialdehyde was also identified. Based on this response and the ability to work at high pH a biosensor for GABA is proposed by coimmobilizing GABA-aminotransferase (GABA-T) and PaoABC in the osmium containing redox polymer.},
  language  = {en}
}
@misc{MogaRobinsonLeimkuehler2019,
  author    = {Moga, A. and Robinson, T. and Leimk{\"u}hler, Silke},
  title     = {Towards reconstituting a biosynthetic pathway within compartmentalized GUVs},
  series = {European biophysics journal : with biophysics letters ; an international journal of biophysics},
  volume    = {48},
  journal   = {European biophysics journal : with biophysics letters ; an international journal of biophysics},
  publisher = {Springer},
  address   = {New York},
  issn      = {0175-7571},
  pages     = {S218 -- S218},
  year      = {2019},
  language  = {en}
}
@article{TangWerchmeisterPredaetal.2019,
  author    = {Tang, Jing and Werchmeister, Rebecka Maria Larsen and Preda, Loredana and Huang, Wei and Zheng, Zhiyong and Leimk{\"u}hler, Silke and Wollenberger, Ulla and Xiao, Xinxin and Engelbrekt, Christian and Ulstrup, Jens and Zhang, Jingdong},
  title     = {Three-dimensional sulfite oxidase bioanodes based on graphene functionalized carbon paper for sulfite/O-2 biofuel cells},
  series = {ACS catalysis},
  volume    = {9},
  journal   = {ACS catalysis},
  number    = {7},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {2155-5435},
  doi       = {10.1021/acscatal.9b01715},
  pages     = {6543 -- 6554},
  year      = {2019},
  abstract  = {We have developed a three-dimensional (3D) graphene electrode suitable for the immobilization of human sulfite oxidase (hSO), which catalyzes the electrochemical oxidation of sulfite via direct electron transfer (DET). The electrode is fabricated by drop-casting graphene-polyethylenimine (G-P) composites on carbon papers (CPs) precoated with graphene oxide (GO). The negatively charged hSO can be adsorbed electrostatically on the positively charged matrix (G-P) on CP electrodes coated with GO (CPG), with a proper orientation for accelerated DET. Notably, further electrochemical reduction of G-P on CPG electrodes leads to a 9-fold increase of the saturation catalytic current density (j(m)) for sulfite oxidation reaching 24.4 +/- 0.3 mu A to cm(-2), the highest value among reported DET-based hSO bioelectrodes. The increased electron transfer rate plays a dominating role in the enhancement of direct enzymatic current because of the improved electric contact of hSO with the electrode, The optimized hSO bioelectrode shows a significant catalytic rate (k(cat): 25.6 +/- 0.3 s(-1)) and efficiency (k(cat)/K-m: 0.231 +/- 0.003 s(-1) mu M-1) compared to the reported hSO bioelectrodes. The assembly of the hSO bioanode and a commercial platinum biocathode allows the construction of sulfite/O-2 enzymatic biofuel cells (EBFCs) with flowing fuels. The optimized EBFC displays an open-circuit voltage (OCV) of 0.64 +/- 0.01 V and a maximum power density of 61 +/- 6 mu W cm(-2) (122 +/- 12 mW m(-3)) at 30 degrees C, which exceeds the best reported value by more than 6 times.},
  language  = {en}
}
@misc{BadalyanDierichStibaetal.2014,
  author    = {Badalyan, Artavazd and Dierich, Marlen and Stiba, Konstanze and Schwuchow, Viola and Leimk{\"u}hler, Silke and Wollenberger, Ulla},
  title     = {Electrical wiring of the aldehyde oxidoreductase PaoABC with a polymer containing osmium redox centers},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {1082},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-47507},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-475070},
  pages     = {21},
  year      = {2014},
  abstract  = {Biosensors for the detection of benzaldehyde and g-aminobutyric acid (GABA) are reported using aldehyde oxidoreductase PaoABC from Escherichia coli immobilized in a polymer containing bound low potential osmium redox complexes. The electrically connected enzyme already electrooxidizes benzaldehyde at potentials below -0.15 V (vs. Ag|AgCl, 1 M KCl). The pH-dependence of benzaldehyde oxidation can be strongly influenced by the ionic strength. The effect is similar with the soluble osmium redox complex and therefore indicates a clear electrostatic effect on the bioelectrocatalytic efficiency of PaoABC in the osmium containing redox polymer. At lower ionic strength, the pH-optimum is high and can be switched to low pH-values at high ionic strength. This offers biosensing at high and low pH-values. A "reagentless" biosensor has been formed with enzyme wired onto a screen-printed electrode in a flow cell device. The response time to addition of benzaldehyde is 30 s, and the measuring range is between 10-150 µM and the detection limit of 5 µM (signal to noise ratio 3:1) of benzaldehyde. The relative standard deviation in a series (n = 13) for 200 µM benzaldehyde is 1.9\%. For the biosensor, a response to succinic semialdehyde was also identified. Based on this response and the ability to work at high pH a biosensor for GABA is proposed by coimmobilizing GABA-aminotransferase (GABA-T) and PaoABC in the osmium containing redox polymer.},
  language  = {en}
}
@article{ZupokGorkaSiemiatkowskaetal.2019,
  author    = {Zupok, Arkadiusz and G{\´o}rka, Michał Jakub and Siemiatkowska, Beata and Skirycz, Aleksandra and Leimk{\"u}hler, Silke},
  title     = {Iron-Dependent Regulation of Molybdenum Cofactor Biosynthesis Genes in Escherichia coli},
  series = {Journal of bacteriology},
  volume    = {201},
  journal   = {Journal of bacteriology},
  number    = {17},
  publisher = {American Society for Microbiology},
  address   = {Washington},
  issn      = {0021-9193},
  doi       = {10.1128/JB.00382-19},
  pages     = {15},
  year      = {2019},
  abstract  = {Molybdenum cofactor (Moco) biosynthesis is a complex process that involves the coordinated function of several proteins. In recent years it has become obvious that the availability of iron plays an important role in the biosynthesis of Moco. First, the MoaA protein binds two (4Fe-4S] clusters per monomer. Second, the expression of the moaABCDE and moeAB operons is regulated by FNR, which senses the availability of oxygen via a functional NFe-4S) cluster. Finally, the conversion of cyclic pyranopterin monophosphate to molybdopterin requires the availability of the L-cysteine desulfurase IscS, which is a shared protein with a main role in the assembly of Fe-S clusters. In this report, we investigated the transcriptional regulation of the moaABCDE operon by focusing on its dependence on cellular iron availability. While the abundance of selected molybdoenzymes is largely decreased under iron-limiting conditions, our data show that the regulation of the moaABCDE operon at the level of transcription is only marginally influenced by the availability of iron. Nevertheless, intracellular levels of Moco were decreased under iron-limiting conditions, likely based on an inactive MoaA protein in addition to lower levels of the L-cysteine desulfurase IscS, which simultaneously reduces the sulfur availability for Moco production. IMPORTANCE FNR is a very important transcriptional factor that represents the master switch for the expression of target genes in response to anaerobiosis. Among the FNR-regulated operons in Escherichia coli is the moaABCDE operon, involved in Moco biosynthesis. Molybdoenzymes have essential roles in eukaryotic and prokaryotic organisms. In bacteria, molybdoenzymes are crucial for anaerobic respiration using alternative electron acceptors. This work investigates the connection of iron availability to the biosynthesis of Moco and the production of active molybdoenzymes.},
  language  = {en}
}
@article{LemaireHonoreTempeletal.2019,
  author    = {Lemaire, Olivier N. and Honore, Flora A. and Tempel, Sebastien and Fortier, Emma M. and Leimk{\"u}hler, Silke and Mejean, Vincent and Iobbi-Nivol, Chantal},
  title     = {Shewanella decolorationis LDS1 Chromate Resistance},
  series = {Applied and environmental microbiology},
  volume    = {85},
  journal   = {Applied and environmental microbiology},
  number    = {18},
  publisher = {American Society for Microbiology},
  address   = {Washington},
  issn      = {0099-2240},
  doi       = {10.1128/AEM.00777-19},
  pages     = {15},
  year      = {2019},
  abstract  = {The genus Shewanella is well known for its genetic diversity, its outstanding respiratory capacity, and its high potential for bioremediation. Here, a novel strain isolated from sediments of the Indian Ocean was characterized. A 16S rRNA analysis indicated that it belongs to the species Shewanella decolorationis. It was named Shewanella decolorationis LDS1. This strain presented an unusual ability to grow efficiently at temperatures from 24 degrees C to 40 degrees C without apparent modifications of its metabolism, as shown by testing respiratory activities or carbon assimilation, and in a wide range of salt concentrations. Moreover, S. decolorationis LDS1 tolerates high chromate concentrations. Indeed, it was able to grow in the presence of 4 mM chromate at 28 degrees C and 3 mM chromate at 40 degrees C. Interestingly, whatever the temperature, when the culture reached the stationary phase, the strain reduced the chromate present in the growth medium. In addition, S. decolorationis LDS1 degrades different toxic dyes, including anthraquinone, triarylmethane, and azo dyes. Thus, compared to Shewanella oneidensis, this strain presented better capacity to cope with various abiotic stresses, particularly at high temperatures. The analysis of genome sequence preliminary data indicated that, in contrast to S. oneidensis and S. decolorationis S12, S. decolorationis LDS1 possesses the phosphorothioate modification machinery that has been described as participating in survival against various abiotic stresses by protecting DNA. We demonstrate that its heterologous production in S. oneidensis allows it to resist higher concentrations of chromate. IMPORTANCE Shewanella species have long been described as interesting microorganisms in regard to their ability to reduce many organic and inorganic compounds, including metals. However, members of the Shewanella genus are often depicted as cold-water microorganisms, although their optimal growth temperature usually ranges from 25 to 28 degrees C under laboratory growth conditions. Shewanella decolorationis LDS1 is highly attractive, since its metabolism allows it to develop efficiently at temperatures from 24 to 40 degrees C, conserving its ability to respire alternative substrates and to reduce toxic compounds such as chromate or toxic dyes. Our results clearly indicate that this novel strain has the potential to be a powerful tool for bioremediation and unveil one of the mechanisms involved in its chromate resistance.},
  language  = {en}
}
@misc{LeimkuehlerBuehningBeilschmidt2017,
  author    = {Leimk{\"u}hler, Silke and B{\"u}hning, Martin and Beilschmidt, Lena},
  title     = {Shared sulfur mobilization routes for tRNA thiolation and molybdenum cofactor biosynthesis in prokaryotes and eukaryotes},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe},
  number    = {1015},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-47501},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-475011},
  pages     = {22},
  year      = {2017},
  abstract  = {Modifications of transfer RNA (tRNA) have been shown to play critical roles in the biogenesis, metabolism, structural stability and function of RNA molecules, and the specific modifications of nucleobases with sulfur atoms in tRNA are present in pro- and eukaryotes. Here, especially the thiomodifications xm(5)s(2)U at the wobble position 34 in tRNAs for Lys, Gln and Glu, were suggested to have an important role during the translation process by ensuring accurate deciphering of the genetic code and by stabilization of the tRNA structure. The trafficking and delivery of sulfur nucleosides is a complex process carried out by sulfur relay systems involving numerous proteins, which not only deliver sulfur to the specific tRNAs but also to other sulfur-containing molecules including iron-sulfur clusters, thiamin, biotin, lipoic acid and molybdopterin (MPT). Among the biosynthesis of these sulfur-containing molecules, the biosynthesis of the molybdenum cofactor (Moco) and the synthesis of thio-modified tRNAs in particular show a surprising link by sharing protein components for sulfur mobilization in pro- and eukaryotes.},
  language  = {en}
}
@misc{ZupokIobbiNivolMejeanetal.2019,
  author    = {Zupok, Arkadiusz and Iobbi-Nivol, Chantal and Mejean, Vincent and Leimk{\"u}hler, Silke},
  title     = {The regulation of Moco biosynthesis and molybdoenzyme gene expression by molybdenum and iron in bacteria},
  series = {Metallomics : integrated biometal science},
  volume    = {11},
  journal   = {Metallomics : integrated biometal science},
  number    = {10},
  publisher = {Royal Society of Chemistry},
  address   = {Cambridge},
  issn      = {1756-5901},
  doi       = {10.1039/c9mt00186g},
  pages     = {1602 -- 1624},
  year      = {2019},
  abstract  = {Bacterial molybdoenzymes are key enzymes involved in the global sulphur, nitrogen and carbon cycles. These enzymes require the insertion of the molybdenum cofactor (Moco) into their active sites and are able to catalyse a large range of redox-reactions. Escherichia coli harbours nineteen different molybdoenzymes that require a tight regulation of their synthesis according to substrate availability, oxygen availability and the cellular concentration of molybdenum and iron. The synthesis and assembly of active molybdoenzymes are regulated at the level of transcription of the structural genes and of translation in addition to the genes involved in Moco biosynthesis. The action of global transcriptional regulators like FNR, NarXL/QP, Fur and ArcA and their roles on the expression of these genes is described in detail. In this review we focus on what is known about the molybdenum- and iron-dependent regulation of molybdoenzyme and Moco biosynthesis genes in the model organism E. coli. The gene regulation in E. coli is compared to two other well studied model organisms Rhodobacter capsulatus and Shewanella oneidensis.},
  language  = {en}
}
@misc{OttoMareljaSchoofsetal.2018,
  author    = {Otto, Nils and Marelja, Zvonimir and Schoofs, Andreas and Kranenburg, Holger and Bittern, Jonas and Yildirim, Kerem and Berh, Dimitri and Bethke, Maria and Thomas, Silke and Rode, Sandra and Risse, Benjamin and Jiang, Xiaoyi and Pankratz, Michael and Leimk{\"u}hler, Silke and Kl{\"a}mbt, Christian},
  title     = {The sulfite oxidase Shopper controls neuronal activity by regulating glutamate homeostasis in Drosophila ensheathing glia},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe},
  number    = {975},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-42620},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-426205},
  pages     = {14},
  year      = {2018},
  abstract  = {Specialized glial subtypes provide support to developing and functioning neural networks. Astrocytes modulate information processing by neurotransmitter recycling and release of neuromodulatory substances, whereas ensheathing glial cells have not been associated with neuromodulatory functions yet. To decipher a possible role of ensheathing glia in neuronal information processing, we screened for glial genes required in the Drosophila central nervous system for normal locomotor behavior. Shopper encodes a mitochondrial sulfite oxidase that is specifically required in ensheathing glia to regulate head bending and peristalsis. shopper mutants show elevated sulfite levels affecting the glutamate homeostasis which then act on neuronal network function. Interestingly, human patients lacking the Shopper homolog SUOX develop neurological symptoms, including seizures. Given an enhanced expression of SUOX by oligodendrocytes, our findings might indicate that in both invertebrates and vertebrates more than one glial cell type may be involved in modulating neuronal activity.},
  language  = {en}
}
@article{HahnewaldLeimkuehlerVilasecaetal.2006,
  author    = {Hahnewald, Rita and Leimk{\"u}hler, Silke and Vilaseca, Antonia and Acquaviva-Bourdain, Cecile and Lenz, Ulrike and Reiss, Jochen},
  title     = {A novel MOCS2 mutation reveals coordinated expression of the small and large subunit of molybdopterin synthase},
  series = {Molecular genetics and metabolism},
  volume    = {89},
  journal   = {Molecular genetics and metabolism},
  number    = {3},
  publisher = {Elsevier},
  address   = {San Diego},
  issn      = {1096-7192},
  doi       = {10.1016/j.ymgme.2006.04.008},
  pages     = {210 -- 213},
  year      = {2006},
  abstract  = {The small and large subunits of molybdopterin (MPT) synthase (MOCS2A and MOCS2B), are both encoded by the MOCS2 gene in overlapping and shifted open reading frames (ORFs), which is a highly unusual structure for eukaryotes. Theoretical analysis of genomic sequences suggested that the expression of these overlapping ORFs is facilitated by the use of alternate first exons leading to alternative transcripts. Here, we confirm the existence of these overlapping transcripts experimentally. Further, we identified a deletion in a molybdenum cofactor deficient patient, which removes the start codon for the small subunit (MOCS2A). We observed undisturbed production of both transcripts, while Western blot analysis demonstrated that MOCS2B, the large subunit, is unstable in the absence of MOCS2A. This reveals new insights into the expression of this evolutionary ancient anabolic system.},
  language  = {en}
}