title: Molybdate-dependent expression of dimethylsulfoxide reductase in Rhodobacter capsulatus.
abstract: Expression of the dimethylsulfoxide respiratory (dor) operon of Rhodobacter is regulated by oxygen, light intensity and availability of substrate. Since dimethylsulfoxide reductase contains a pterin molybdenum cofactor, the role of molybdate in the regulation of dor operon expression was investigated. In this report we show that the molybdate-responsive transcriptional regulator, MopB, and molybdate are essential for maximal dimethylsulfoxide reductase activity and expression of a dorA::lacZ transcriptional fusion in Rhodobacter capsulatus. In contrast, mop genes are not required for the expression of the periplasmic nitrate reductase or xanthine dehydrogenase in R. capsulatus under conditions of molybdenum sufficiency. This is the first report demonstrating a clear functional difference between the ModE homologues MopB and MopA in this bacterium. The results suggest that MopA is primarily involved in the regulation of nitrogen fixation gene expression in response to molybdate while MopB has a role in nitrogen fixation and dimethylsulfoxide respiration.
authors.affiliation: Department of Microbiology and Parasitology, The University of Queensland, Brisbane, Australia.
authors.forename: P S
authors.initials: PS
authors.lastname: Solomon
authors.forename: A L
authors.initials: AL
authors.lastname: Shaw
authors.forename: M D
authors.initials: MD
authors.lastname: Young
authors.forename: S
authors.initials: S
authors.lastname: Leimkuhler
authors.forename: G R
authors.initials: GR
authors.lastname: Hanson
authors.forename: W
authors.initials: W
authors.lastname: Klipp
authors.forename: A G
authors.initials: AG
authors.lastname: McEwan
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins; D015964:Gene Expression Regulation, Bacterial; D007506:Iron-Sulfur Proteins; D007763:Lac Operon / Q000502:physiology; D026901:Membrane Transport Proteins; D008982:Molybdenum / Q000378:metabolism*; D009154:Mutation; D009565:Nitrate Reductases / Q000378:metabolism; D009876:Operon / Q000235:genetics; D010088:Oxidoreductases / Q000235:genetics* / Q000378:metabolism*; D019897:Periplasm / Q000201:enzymology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016354:Rhodobacter capsulatus / Q000201:enzymology* / Q000235:genetics; D014158:Transcription, Genetic; D014969:Xanthine Oxidase / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D007506:Iron-Sulfur Proteins; D026901:Membrane Transport Proteins; D011993:Recombinant Fusion Proteins; C081166:mopA protein, Rhodobacter capsulatus; C081167:mopB protein, Rhodobacter capsulatus; C044659:molybdate; D008982:Molybdenum; D010088:Oxidoreductases; D014969:Xanthine Oxidase; D009565:Nitrate Reductases; C045664:dimethyl sulfoxide reductase