@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{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{BuehningFriemelLeimkuehler2017,
  author    = {B{\"u}hning, Martin and Friemel, Martin and Leimk{\"u}hler, Silke},
  title     = {Functional Complementation Studies Reveal Different Interaction Partners of Escherichia coil IscS and Human NFS1},
  series = {Biochemistry},
  volume    = {56},
  journal   = {Biochemistry},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0006-2960},
  doi       = {10.1021/acs.biochem.7b00627},
  pages     = {4592 -- 4605},
  year      = {2017},
  abstract  = {The trafficking and delivery of sulfur to cofactors and nucleosides is a highly regulated and conserved process among all organisms. All sulfur transfer pathways generally have an L-cysteine desulfurase as an initial sulfur mobilizing enzyme in common, which serves as a sulfur donor for the biosynthesis of sulfur-containing biomolecules like iron sulfur (Fe-S) clusters, thiamine, biotin, lipoic acid, the molybdenum cofactor (Moco), and thiolated nucleosides in tRNA. The human L-cysteine desulfurase NFS1 and the Escherichia coli homologue IscS share a level of amino acid sequence identity of similar to 60\%. While E. coli IscS has a versatile role in the cell and was shown to have numerous interaction partners, NFS1 is mainly localized in mitochondria with a crucial role in the biosynthesis of Fe-S clusters. Additionally, NFS1 is also located in smaller amounts in the cytosol with a role in Moco biosynthesis and mcm(5)s(2)U34 thio modifications of nucleosides in tRNA. NFS1 and IscS were conclusively shown to have different interaction partners in their respective organisms. Here, we used functional complementation studies of an E. coli iscS deletion strain with human NFS1 to dissect their conserved roles in the transfer of sulfur to a specific target protein. Our results show that human NFS1 and E. coli IscS share conserved binding sites for proteins involved in Fe-S cluster assembly like IscU, but not with proteins for tRNA thio modifications or Moco biosynthesis. In addition, we show that human NFS1 was almost fully able to complement the role of IscS in Moco biosynthesis when its specific interaction partner protein MOCS3 from humans was also present.},
  language  = {en}
}
@phdthesis{Buehning2018,
  author    = {B{\"u}hning, Martin},
  title     = {Charakterisierung des Zusammenspiels von FeS-Cluster-Assemblierung, Molybd{\"a}nkofaktor-Biosynthese und tRNA-Thiolierung in Escherichia coli},
  school      = {Universit{\"a}t Potsdam},
  pages     = {167},
  year      = {2018},
  language  = {de}
}
@article{DahlRadonBuehningetal.2013,
  author    = {Dahl, Jan-Ulrik and Radon, Christin and B{\"u}hning, Martin and Nimtz, Manfred and Leichert, Lars I. and Denis, Yann and Jourlin-Castelli, Cecile and Iobbi-Nivol, Chantal and Mejean, Vincent and Leimk{\"u}hler, Silke},
  title     = {The Sulfur Carrier Protein TusA Has a Pleiotropic Role in Escherichia coli That Also Affects Molybdenum Cofactor Biosynthesis},
  series = {JOURNAL OF BIOLOGICAL CHEMISTRY},
  volume    = {288},
  journal   = {JOURNAL OF BIOLOGICAL CHEMISTRY},
  number    = {8},
  publisher = {AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC},
  address   = {BETHESDA},
  issn      = {0021-9258},
  doi       = {10.1074/jbc.M112.431569},
  pages     = {5426 -- 5442},
  year      = {2013},
  abstract  = {The Escherichia coli L-cysteine desulfurase IscS mobilizes sulfur from L-cysteine for the synthesis of several biomolecules such as iron-sulfur (FeS) clusters, molybdopterin, thiamin, lipoic acid, biotin, and the thiolation of tRNAs. The sulfur transfer from IscS to various biomolecules is mediated by different interaction partners (e.g. TusA for thiomodification of tRNAs, IscU for FeS cluster biogenesis, and ThiI for thiamine biosynthesis/tRNA thiolation), which bind at different sites of IscS. Transcriptomic and proteomic studies of a Delta tusA strain showed that the expression of genes of the moaABCDE operon coding for proteins involved in molybdenum cofactor biosynthesis is increased under aerobic and anaerobic conditions. Additionally, under anaerobic conditions the expression of genes encoding hydrogenase 3 and several molybdoenzymes such as nitrate reductase were also increased. On the contrary, the activity of all molydoenzymes analyzed was significantly reduced in the Delta tusA mutant. Characterization of the Delta tusA strain under aerobic conditions showed an overall low molybdopterin content and an accumulation of cyclic pyranopterin monophosphate. Under anaerobic conditions the activity of nitrate reductase was reduced by only 50\%, showing that TusA is not essential for molybdenum cofactor biosynthesis. We present a model in which we propose that the direction of sulfur transfer for each sulfur-containing biomolecule is regulated by the availability of the interaction partner of IscS. We propose that in the absence of TusA, more IscS is available for FeS cluster biosynthesis and that the overproduction of FeS clusters leads to a modified expression of several genes.},
  language  = {en}
}