title: Spectroscopic characterization of the molybdenum cofactor of the sulfane dehydrogenase SoxCD from Paracoccus pantotrophus.
abstract: The bacterial sulfane dehydrogenase SoxCD is a distantly related member of the sulfite oxidase (SO) enzyme family that is proposed to oxidize protein-bound sulfide (sulfane) of SoxY as part of a multienzyme mechanism of thiosulfate metabolism. This study characterized the molybdenum cofactor of SoxCD1, comprising the catalytic molybdopterin subunit SoxC and the truncated c-type cytochrome subunit SoxD1. Electron paramagnetic resonance spectroscopy of the Mo(V) intermediate generated by dithionite reduction revealed low- and high-pH species with g and A((95,97)Mo) matrices nearly identical to those of SO, indicating a similar pentacoordinate active site in SoxCD1. However, no sulfite-induced reduction to Mo(V) was detected, nor could a strongly coupled (1)H signal or a phosphate-inhibited species be generated. This indicates that the outer coordination sphere controls substrate binding in SoxCD, permitting access only to protein-bound sulfur via the C-terminal tail of SoxY.
authors.affiliation: Max-Planck-Institut für Bioanorganische Chemie, 45470 Mülheim an der Ruhr, Germany.
authors.forename: Simon C
authors.initials: SC
authors.lastname: Drew
authors.forename: Eduard
authors.initials: E
authors.lastname: Reijerse
authors.forename: Armin
authors.initials: A
authors.lastname: Quentmeier
authors.forename: Dagmar
authors.initials: D
authors.lastname: Rother
authors.forename: Cornelius G
authors.initials: CG
authors.lastname: Friedrich
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Lubitz
mesh_terms: D020134:Catalytic Domain; D002712:Chlorides / Q000737:chemistry; D003067:Coenzymes / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D008667:Metalloproteins / Q000737:chemistry*; D000090006:Molybdenum Cofactors; D042084:Paracoccus pantotrophus / Q000201:enzymology* / Q000235:genetics; D011621:Pteridines / Q000737:chemistry*; D013455:Sulfur / Q000737:chemistry
chemical_list: D002712:Chlorides; D003067:Coenzymes; D008024:Ligands; D008667:Metalloproteins; D000090006:Molybdenum Cofactors; D011621:Pteridines; D013455:Sulfur; C022261:molybdopterin