Sone N, Fukuda M, Katayama S, Jyoudai A, Syugyou M, Noguchi S, Sakamoto J. QcrCAB operon of a nocardia-form actinomycete Rhodococcus rhodochrous encodes cytochrome reductase complex with diheme cytochrome cc subunit.
Biochim Biophys Acta 2003;
1557:125-31. [PMID:
12615356 DOI:
10.1016/s0005-2728(02)00394-8]
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Abstract
Structural genes encoding quinol-cytochrome c reductase (QcR) were cloned and sequenced from nocardia-form actinomycete Rhodococcus rhodochrous. QcrC and qcrA encode diheme cytochrome cc and the Rieske Fe-S protein, respectively, while the qcrB product is a diheme cytochrome b. These amino acid sequences are similar to those of Corynebacterium and Mycobacterium, the members of high G+C content firmicutes. The presence of diheme cytochrome cc subunit as a sole c-type cytochrome in these organisms suggests the direct elecron transfer to cytochrome c oxidase. The N-terminal half of the Rieske Fe-S proteins of these bacteria has a unique structure with three transmembrane helices, while the C-terminal half sequence is conserved. A phylogenetic tree using the latter region showed that high G+C firmicutes form a clear clade with Thermus, but not with low G+C firmicutes.
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