Multiple haem lyase genes indicate substrate specificity in cytochrome c biogenesis.
c-Type cytochromes are a widespread class of proteins that play a vital role in the energy-conserving metabolism of prokaryotic and eukaryotic organisms. The key event in cytochrome c biogenesis is the covalent attachment of the haem cofactor to two (or rarely one) cysteine residues arranged in a haem c-binding motif such as CX(2-4)CH, CXXCK or X(3)CH. This reaction is catalysed by the membrane-bound enzyme CCHL (cytochrome c haem lyase). Different CCHLs have been described and some of them are dedicated to distinct haem c-binding motifs of cytochromes that are encoded in the vicinity of the respective CCHL gene. Various bacterial genomes contain multiple copies of CCHL-encoding genes, suggesting the presence of non-conventional or even as yet unrecognized haem c-binding motifs. This assumption is exemplified in the present study using the proteobacterium Wolinella succinogenes as a model organism whose genome encodes three CCHL isoenzymes. The discovery of a novel conserved multihaem cytochrome c (MccA) is described.
Hartshorne
S
S
School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK.
Richardson
D J
DJ
Simon
J
J
D020816:Amino Acid Motifs; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D003574:Cytochrome c Group / Q000096:biosynthesis*; D006418:Heme / Q000378:metabolism*; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008190:Lyases / Q000235:genetics* / Q000378:metabolism; D013379:Substrate Specificity; D016968:Wolinella / Q000201:enzymology / Q000235:genetics
D001426:Bacterial Proteins; D003574:Cytochrome c Group; D007527:Isoenzymes; D006418:Heme; D008190:Lyases; C031581:cytochrome C synthetase