TY - JOUR A1 - Mendel, Ralf R. A1 - Leimkühler, Silke T1 - The biosynthesis of the molybdenum cofactors JF - Journal of biological inorganic chemistry N2 - The biosynthesis of the molybdenum cofactors (Moco) is an ancient, ubiquitous, and highly conserved pathway leading to the biochemical activation of molybdenum. Moco is the essential component of a group of redox enzymes, which are diverse in terms of their phylogenetic distribution and their architectures, both at the overall level and in their catalytic geometry. A wide variety of transformations are catalyzed by these enzymes at carbon, sulfur and nitrogen atoms, which include the transfer of an oxo group or two electrons to or from the substrate. More than 50 molybdoenzymes were identified to date. In all molybdoenzymes except nitrogenase, molybdenum is coordinated to a dithiolene group on the 6-alkyl side chain of a pterin called molybdopterin (MPT). The biosynthesis of Moco can be divided into three general steps, with a fourth one present only in bacteria and archaea: (1) formation of the cyclic pyranopterin monophosphate, (2) formation of MPT, (3) insertion of molybdenum into molybdopterin to form Moco, and (4) additional modification of Moco in bacteria with the attachment of a nucleotide to the phosphate group of MPT, forming the dinucleotide variant of Moco. This review will focus on the biosynthesis of Moco in bacteria, humans and plants. KW - Molybdenum KW - Molybdenum cofactor KW - cPMP KW - bis-MGD KW - Sulfuration KW - Sulfite oxidase Y1 - 2015 U6 - https://doi.org/10.1007/s00775-014-1173-y SN - 0949-8257 SN - 1432-1327 VL - 20 IS - 2 SP - 337 EP - 347 PB - Springer CY - New York ER - TY - JOUR A1 - Fraesdorf, Benjamin A1 - Radon, Christin A1 - Leimkühler, Silke T1 - Characterization and interaction studies of two isoforms of the dual localized 3-mercaptopyruvate sulfurtransferase TUM1 from humans JF - The journal of biological chemistry N2 - Background: Localization and identification of interaction partners of two splice variants of the human 3-mercaptopyruvate sulfurtransferase TUM1. Results: We show that TUM1 interacts with proteins involved in Moco and FeS cluster biosynthesis. Conclusion: Human TUM1 is a dual localized protein in the cytosol and mitochondria with distinct roles in sulfur transfer and interaction partners. Significance: The study contributes to the sulfur transfer pathway for the biosynthesis of sulfur-containing biofactors. The human tRNA thiouridine modification protein (TUM1), also designated as 3-mercaptopyruvate sulfurtransferase (MPST), has been implicated in a wide range of physiological processes in the cell. The roles range from an involvement in thiolation of cytosolic tRNAs to the generation of H2S as signaling molecule both in mitochondria and the cytosol. TUM1 is a member of the sulfurtransferase family and catalyzes the conversion of 3-mercaptopyruvate to pyruvate and protein-bound persulfide. Here, we purified and characterized two novel TUM1 splice variants, designated as TUM1-Iso1 and TUM1-Iso2. The purified proteins showed similar kinetic behavior and comparable pH and temperature dependence. Cellular localization studies, however, showed a different localization pattern between the isoforms. TUM1-Iso1 is exclusively localized in the cytosol, whereas TUM1-Iso2 showed a dual localization both in the cytosol and mitochondria. Interaction studies were performed with the isoforms both in vitro using the purified proteins and in vivo by fluorescence analysis in human cells, using the split-EGFP system. The studies showed that TUM1 interacts with the l-cysteine desulfurase NFS1 and the rhodanese-like protein MOCS3, suggesting a dual function of TUM1 both in sulfur transfer for the biosynthesis of the molybdenum cofactor, and for the thiolation of tRNA. Our studies point to distinct roles of each TUM1 isoform in the sulfur transfer processes in the cell, with different compartmentalization of the two splice variants of TUM1. KW - Fluorescence KW - Mitochondria KW - Molybdenum KW - Sulfur KW - Transfer RNA (tRNA) Y1 - 2014 U6 - https://doi.org/10.1074/jbc.M114.605733 SN - 0021-9258 SN - 1083-351X VL - 289 IS - 50 SP - 34543 EP - 34556 PB - American Society for Biochemistry and Molecular Biology CY - Bethesda ER - TY - JOUR A1 - Samuel, Prinson P. A1 - Horn, Sebastian A1 - Döring, Alexander A1 - Havelius, Kajsa G. V. A1 - Reschke, Stefan A1 - Leimkühler, Silke A1 - Haumann, Michael A1 - Schulzke, Carola T1 - A Crystallographic and Mo K-Edge XAS Study of Molybdenum Oxo Bis-,Mono-, and Non-Dithiolene Complexes - First-Sphere Coordination Geometry and Noninnocence of Ligands JF - European journal of inorganic chemistry : a journal of ChemPubSoc Europe N2 - Ten square-based pyramidal molybdenum complexes with different sulfur donor ligands, that is, a variety of dithiolenes and sulfides, were prepared, which mimic coordination motifs of the molybdenum cofactors of molybdenum-dependent oxidoreductases. The model compounds were investigated by Mo K-edge X-ray absorption spectroscopy (XAS) and (with one exception) their molecular structures were analyzed by X-ray diffraction to derive detailed information on bond lengths and geometries of the first coordination shell of molybdenum. Only small variations in Mo=O and Mo-S bond lengths and their respective coordination angles were observed for all complexes including those containing Mo(CO)(2) or Mo(mu-S)(2)Mo motifs. XAS analysis (edge energy) revealed higher relative oxidation levels in the molybdenum ion in compounds with innocent sulfur-based ligands relative to those in dithiolene complexes, which are known to exhibit noninnocence, that is, donation of substantial electron density from ligand to metal. In addition, longer average Mo-S and Mo=O bonds and consequently lower.(Mo=O) stretching frequencies in the IR spectra were observed for complexes with dithiolene-derived ligands. The results emphasize that the noninnocent character of the dithiolene ligand influences the electronic structure of the model compounds, but does not significantly affect their metal coordination geometry, which is largely determined by the Mo(IV) or (V) ion itself. The latter conclusion also holds for the molybdenum site geometries in the oxidized Mo-VI cofactor of DMSO reductase and the reduced Mo-IV cofactor of arsenite oxidase. The innocent behavior of the dithiolene molybdopterin ligands observed in the enzymes is likely to be related to cofactor-protein interactions. KW - Molybdenum KW - Enzyme models KW - X-ray absorption spectroscopy KW - Noninnocence KW - Bioinorganic chemistry Y1 - 2011 U6 - https://doi.org/10.1002/ejic.201100331 SN - 1434-1948 IS - 28 SP - 4387 EP - 4399 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Iobbi-Nivol, Chantal A1 - Leimkühler, Silke T1 - Molybdenum enzymes, their maturation and molybdenum cofactor biosynthesis in Escherichia coli JF - Biochimica et biophysica acta : Bioenergetics N2 - Molybdenum cofactor (Moco) biosynthesis is an ancient, ubiquitous, and highly conserved pathway leading to the biochemical activation of molybdenum. Moco is the essential component of a group of redox enzymes, which are diverse in terms of their phylogenetic distribution and their architectures, both at the overall level and in their catalytic geometry. A wide variety of transformations are catalyzed by these enzymes at carbon, sulfur and nitrogen atoms, which include the transfer of an oxo group or two electrons to or from the substrate. More than 50 molybdoenzymes were identified in bacteria to date. In molybdoenzymes Mo is coordinated to a dithiolene group on the 6-alkyl side chain of a pterin called molybdopterin (MPT). The biosynthesis of Moco can be divided into four general steps in bacteria: I) formation of the cyclic pyranopterin monophosphate, 2) formation of MPT, 3) insertion of molybdenum into molybdopterin to form Moco, and 4) additional modification of Moco with the attachment of GMP or CMP to the phosphate group of MPT, forming the dinucleotide variant of Moco. This review will focus on molybdoenzymes, the biosynthesis of Moco, and its incorporation into specific target proteins focusing on Escherichia coli. This article is part of a Special Issue entitled: Metals in Bioenergetics and Biomimetics Systems. KW - Molybdenum cofactor KW - Molybdenum KW - Dithiolene KW - Molybdopterin KW - Bis-MGD KW - Moco Y1 - 2013 U6 - https://doi.org/10.1016/j.bbabio.2012.11.007 SN - 0005-2728 VL - 1827 IS - 8-9 SP - 1086 EP - 1101 PB - Elsevier CY - Amsterdam ER -