title: Genomics of the ccoNOQP-encoded cbb3 oxidase complex in bacteria.
abstract: Many bacteria adapt to microoxic conditions by synthesizing a particular cytochrome c oxidase (cbb3) complex with a high affinity for O2, encoded by the ccoNOQP operon. A survey of genome databases indicates that ccoNOQP sequences are widespread in all sub-branches of Proteobacteria but otherwise are found only in bacteria of the CFB group ( Cytophaga, Flexibacter, Bacteroides). Our analysis of available genome sequences suggests four major strategies of regulating ccoNOQP expression in response to O2. The most widespread strategy involves direct regulation by the O2-responsive protein Fnr. The second strategy involves an O2-insensitive paralogue of Fnr, FixK, whose expression is regulated by the O2-responding FixLJ two-component system. A third strategy of mixed regulation operates in bacteria carrying both fnr and fixLJ-fixKgenes. Another, not yet identified, strategy is likely to operate in the epsilon-Proteobacteria Helicobacter pylori and Campylobacter jejuni which lack fnr and fixLJ-fixK genes. The FixLJ strategy appears specific for the alpha-subclass of Proteobacteria but is not restricted to rhizobia in which it was originally discovered.
authors.affiliation: Laboratoire des Interactions Plantes-Micro-organismes, UMR CNRS-INRA 2594/441, BP27, 31326 Castanet Tolosan cedex, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Cosseau
authors.forename: Jacques
authors.initials: J
authors.lastname: Batut
mesh_terms: D001419:Bacteria / Q000201:enzymology* / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology; D003576:Electron Transport Complex IV / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D006420:Hemeproteins / Q000235:genetics / Q000502:physiology; D000071677:Histidine Kinase; D009876:Operon; D010100:Oxygen / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; D006420:Hemeproteins; D014157:Transcription Factors; C066628:FixK protein, Bacteria; C069289:FixJ protein, Bacteria; C414443:cbb3 oxidase; D003576:Electron Transport Complex IV; C067929:FixL protein, Bacteria; D000071677:Histidine Kinase; D010100:Oxygen