title: The structure of the periplasmic thiol-disulfide oxidoreductase SoxS from Paracoccus pantotrophus indicates a triple Trx/Grx/DsbC functionality in chemotrophic sulfur oxidation.
abstract: The periplasmic thiol-disulfide oxidoreductase SoxS is beneficial for the sulfur-oxidizing (Sox) phenotype of the facultative chemotrophic bacterium Paracoccus pantotrophus and is not part of the Sox enzyme system. SoxS combines features of thioredoxins, glutaredoxins and the thiol-disulfide oxidoreductases of the Dsb family in structure, target specificity and reaction. The structure of SoxS was solved in oxidized and reduced forms at 2.1 and 1.9 A resolution, respectively. SoxS revealed high structural homology to typical cytoplasmic bacterial thioredoxins. In contrast, SoxS contained the active-site motif Pro-Gly-Cys-Leu-Tyr-Cys that is not present in other thioredoxins. Interestingly, the sequence of this motif is closely related to the Pro-Gly-Cys-Pro-Tyr-Cys sequence of some glutaredoxins and to the Pro-Xaa-Cys-Xaa-Tyr-Cys sequences of some members of the DsbC and DsbG subfamilies of thiol-disulfide oxidoreductases. Furthermore, the proposed substrate of SoxS, the interprotein disulfide of SoxY, Cys110(Y)-Cys110(Y), is structurally similar to oxidized glutathione. However, SoxS is proposed to specifically reduce the interprotein disulfide between two SoxY subunits, releasing a heterodimeric SoxYZ as an active part of the sulfur-oxidation cycle.
authors.affiliation: Abteilung für Strukturbiologie, Zoologisches Institut, Christian-Albrechts-Universität zu Kiel, Kiel, Germany.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Carius
authors.forename: Dagmar
authors.initials: D
authors.lastname: Rother
authors.forename: Cornelius G
authors.initials: CG
authors.lastname: Friedrich
authors.forename: Axel J
authors.initials: AJ
authors.lastname: Scheidig
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology; D001665:Binding Sites; D018360:Crystallography, X-Ray; D019281:Dimerization; D004220:Disulfides / Q000378:metabolism; D054477:Glutaredoxins / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000378:metabolism; D042084:Paracoccus pantotrophus / Q000201:enzymology*; D011487:Protein Conformation; D011490:Protein Disulfide Reductase (Glutathione) / Q000737:chemistry* / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D012645:Selenomethionine / Q000737:chemistry; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D013455:Sulfur / Q000378:metabolism*; D013879:Thioredoxins / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D004220:Disulfides; D054477:Glutaredoxins; D011993:Recombinant Fusion Proteins; D013879:Thioredoxins; D013455:Sulfur; D012645:Selenomethionine; D050862:Oxidoreductases Acting on Sulfur Group Donors; C413329:SoxZ protein, Paracoccus pantotrophus; D011490:Protein Disulfide Reductase (Glutathione)