Optical study of cytochrome cM formation in Synechocystis.
The expression of the cytM gene, which encodes cytochrome cM in Synechocystis sp. PCC 6803, is induced under stress conditions such as low temperature. Results of spectrophotometric studies revealed that cytochrome cM was oxidized by light absorbed by photosystem I in cells that had acclimatized to a low temperature. However, no similar light-induced oxidation of cytochrome cM was observed in delta cytM mutant cells. The kinetics of the oxidation and reduction of P700 before and after acclimation of Synechocystis cells to low temperature suggested that cytochrome cM might donate electrons to photooxidized P700. Our observations indicate that cytochrome cM is synthesized under low-temperature stress and that it might carry electrons directly to P700+ in photosystem I.
Shuvalov
V A
VA
Department of Regulation Biology, National Institute for Basic Biology, Myodaiji, Okazaki, Japan. shuvalov@issp.serpukhov.su
Allakhverdiev
S I
SI
Sakamoto
A
A
Malakhov
M
M
Murata
N
N
D001426:Bacterial Proteins; D000458:Cyanobacteria / Q000201:enzymology*; D003574:Cytochrome c Group / Q000096:biosynthesis* / Q000378:metabolism / Q000528:radiation effects; D005798:Genes, Bacterial; D007700:Kinetics; D008027:Light; D010084:Oxidation-Reduction; D013056:Spectrophotometry, Ultraviolet
D001426:Bacterial Proteins; D003574:Cytochrome c Group; C117990:cytochrome c(M), Synechocystis