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Arch Microbiol. 2004 Feb;181(2):89-96. Epub 2004 Jan 9.

Genomics of the ccoNOQP-encoded cbb3 oxidase complex in bacteria.

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Laboratoire des Interactions Plantes-Micro-organismes, UMR CNRS-INRA 2594/441, BP27, 31326 Castanet Tolosan cedex, France.


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.

[Indexed for MEDLINE]

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