Cytochrome c(6A) is a funnel for thiol oxidation in the thylakoid lumen.
Cytochrome c(6A) is a dithio-cytochrome recently discovered in land plants and green algae, and believed to be derived from the well-known cytochrome c(6). The function of cytochrome c(6A) is unclear. We propose that it catalyses the formation of disulphide bridges in thylakoid lumen proteins in a single-step disulphide exchange reaction, with subsequent transfer of the reducing equivalents to plastocyanin. The haem group of cytochrome c(6A) acts as an electron sink, allowing rapid resolution of a radical intermediate formed during reoxidation of cytochrome c(6A). Our model is consistent with previously published data on mutant plants, and the likely evolution of the protein.
Schlarb-Ridley
Beatrix G
BG
Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK.
Nimmo
Robert H
RH
Purton
Saul
S
Howe
Christopher J
CJ
Bendall
Derek S
DS
D020418:Algal Proteins / Q000235:genetics / Q000378:metabolism*; D045365:Cytochromes c6 / Q000235:genetics / Q000378:metabolism*; D004220:Disulfides / Q000378:metabolism; D056890:Eukaryota / Q000378:metabolism*; D010084:Oxidation-Reduction; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D010944:Plants / Q000235:genetics / Q000378:metabolism*; D010970:Plastocyanin / Q000235:genetics / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000378:metabolism; D020524:Thylakoids / Q000235:genetics / Q000378:metabolism*
D020418:Algal Proteins; D045365:Cytochromes c6; D004220:Disulfides; D010940:Plant Proteins; D013438:Sulfhydryl Compounds; D010970:Plastocyanin