title: SoxV transfers electrons to the periplasm of Paracoccus pantotrophus - an essential reaction for chemotrophic sulfur oxidation.
abstract: The soxVW genes are located upstream of the sox gene cluster encoding the sulfur-oxidizing ability of Paracoccus pantotrophus. SoxV is highly homologous to CcdA, which is involved in cytochrome c maturation of P. pantotrophus. SoxV was shown to function in reduction of the periplasmic SoxW, which shows a CysXaaXaaCys motif characteristic for thioredoxins. From strain GBOmegaV, which carries an Omega-kanamycin-resistance-encoding interposon in soxV, and complementation analysis it was evident that SoxV but not the periplasmic SoxW was essential for lithoautotrophic growth of P. pantotrophus with thiosulfate. However, the thiosulfate-oxidizing activities of cell extracts from the wild-type and from strain GBOmegaV were similar, demonstrating that the low thiosulfate-oxidizing activity of strain GBOmegaV in vivo was not due to a defect in biosynthesis or maturation of proteins of the Sox system and suggesting that SoxV is part of a regulatory or catalytic system of the Sox system. Analysis of DNA sequences available from different organisms harbouring a Sox system revealed that soxVW genes are exclusively present in sox operons harbouring the soxCD genes, encoding sulfur dehydrogenase, suggesting that SoxCD might be a redox partner of SoxV. No complementation of the ccdA mutant P. pantotrophus TP43 defective in cytochrome c maturation was achieved by expression of soxV in trans, demonstrating that the high identity of SoxV and CcdA does not correspond to functional homology.
authors.affiliation: Lehrstuhl für Technische Mikrobiologie, Fachbereich Bio- und Chemieingenieurwesen, Universität Dortmund, D-44221 Dortmund, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Bardischewsky
authors.affiliation: Lehrstuhl für Technische Mikrobiologie, Fachbereich Bio- und Chemieingenieurwesen, Universität Dortmund, D-44221 Dortmund, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Fischer
authors.affiliation: Lehrstuhl für Technische Mikrobiologie, Fachbereich Bio- und Chemieingenieurwesen, Universität Dortmund, D-44221 Dortmund, Germany.
authors.forename: Bettina
authors.initials: B
authors.lastname: Höller
authors.affiliation: Lehrstuhl für Technische Mikrobiologie, Fachbereich Bio- und Chemieingenieurwesen, Universität Dortmund, D-44221 Dortmund, Germany.
authors.forename: Cornelius G
authors.initials: CG
authors.lastname: Friedrich
mesh_terms: D003574:Cytochrome c Group / Q000235:genetics / Q000378:metabolism*; D004583:Electrons; D015964:Gene Expression Regulation, Bacterial; D042084:Paracoccus pantotrophus / Q000235:genetics / Q000378:metabolism*; D019897:Periplasm / Q000378:metabolism; D013455:Sulfur / Q000378:metabolism*
chemical_list: D003574:Cytochrome c Group; D013455:Sulfur