title: The ccoNOQP gene cluster codes for a cb-type cytochrome oxidase that functions in aerobic respiration of Rhodobacter capsulatus.
abstract: The genes for a new type of a haem-copper cytochrome oxidase were cloned from Rhodobacter capsulatus strain 37b4, using the Bradyrhizobium japonicum fixNOQP gene region as a hybridizing probe. Four genes, probably organized in an operon (ccoNOQP), were identified; their products share extensive amino acid sequence similarity with the FixN, O, Q and P proteins that have recently been shown to be the subunits of a cb-type oxidase. CcoN is a b-type cytochrome, CcoO and CcoP are membrane-bound mono- and dihaem c-type cytochromes and CcoQ is a small membrane protein of unknown function. Genes for a similar oxidase are also present in other non-rhizobial bacterial species such as Azotobacter vinelandii, Agrobacterium tumefaciens and Pseudomonas aeruginosa, as revealed by polymerase chain reaction analysis. A ccoN mutant was constructed whose phenotype, in combination with the structural information on the gene products, provides evidence that the CcoNOQP oxidase is a cytochrome c oxidase of the cb type, which supports aerobic respiration in R. capsulatus and which is probably identical to the cbb3-type oxidase that was recently purified from a different strain of the same species. Mutant analysis also showed that this oxidase has no influence on photosynthetic growth and nitrogen-fixation activity.
authors.affiliation: Mikrobiologisches Institut, Eidgenössische Technische Hochschule, ETH-Zentrum, Zürich, Switzerland.
authors.forename: L
authors.initials: L
authors.lastname: Thöny-Meyer
authors.forename: C
authors.initials: C
authors.lastname: Beck
authors.forename: O
authors.initials: O
authors.lastname: Preisig
authors.forename: H
authors.initials: H
authors.lastname: Hennecke
mesh_terms: D000332:Aerobiosis; D000595:Amino Acid Sequence; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D003576:Electron Transport Complex IV / Q000145:classification / Q000235:genetics* / Q000378:metabolism*; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D005810:Multigene Family; D009154:Mutation; D009586:Nitrogen Fixation / Q000235:genetics; D011550:Pseudomonas aeruginosa / Q000201:enzymology / Q000235:genetics; D012230:Rhizobiaceae / Q000201:enzymology / Q000235:genetics; D012231:Rhizobium / Q000201:enzymology / Q000235:genetics; D016354:Rhodobacter capsulatus / Q000201:enzymology* / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
chemical_list: D017931:DNA Primers; D004269:DNA, Bacterial; D003576:Electron Transport Complex IV