We demonstrate that the cccB gene, identified in the Bacillus subtilis genome sequence project, is the structural gene for a 10-kDa membrane-bound cytochrome c551 lipoprotein described for the first time in B. subtilis. Apparently, CccB corresponds to cytochrome c551 of the thermophilic bacterium Bacillus PS3. The heme domain of B. subtilis cytochrome c551 is very similar to that of cytochrome c550, a protein encoded by the cccA gene and anchored to the membrane by a single transmembrane polypeptide segment. Thus, B. subtilis contains two small, very similar, c-type cytochromes with different types of membrane anchors. The cccB gene is cotranscribed with the yvjA gene, and transcription is repressed by glucose. Mutants deleted for cccB or yvjA-cccB show no apparent growth, sporulation, or germination defect. YvjA is not required for the synthesis of cytochrome c551, and its function remains unknown.
NATURVETENSKAP -- Biologiska vetenskaper -- Biokemi och molekylärbiologi (hsv//swe)