Cytochrome c-553 is not required for photosynthetic activity in the cyanobacterium Synechococcus.
In cyanobacteria, the water-soluble cytochrome c-553 functions as a mobile carrier of electrons between the membrane-bound cytochrome b6-f complex and P-700 reaction centers of Photosystem I. The structural gene for cytochrome c-553 (designated cytA) of the cyanobacterium Synechococcus sp. PCC 7942 was cloned, and the deduced amino acid sequence was shown to be similar to known cyanobacterial cytochrome c-553 proteins. A deletion mutant was constructed that had no detectable cytochrome c-553 based on spectral analyses and tetramethylbenzidine-hydrogen peroxide staining of proteins resolved by polyacrylamide gel electrophoresis. The mutant strain was not impaired in overall photosynthetic activity. However, this mutant exhibited a decreased efficiency of cytochrome f oxidation. These results indicate that cytochrome c-553 is not an absolute requirement for reducing Photosystem I reaction centers in Synechococcus sp. PCC 7942.
Laudenbach
D E
DE
Carnegie Institution of Washington, Department of Plant Biology, Stanford, California 94305.
Herbert
S K
SK
McDowell
C
C
Fork
D C
DC
Grossman
A R
AR
Straus
N A
NA
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D003001:Cloning, Molecular; D000458:Cyanobacteria / Q000201:enzymology* / Q000235:genetics; D003574:Cytochrome c Group / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015342:DNA Probes / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D005798:Genes, Bacterial / Q000235:genetics; D008969:Molecular Sequence Data; D016296:Mutagenesis / Q000235:genetics; D009572:Nitrite Reductases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism; D015183:Restriction Mapping
D001426:Bacterial Proteins; D003574:Cytochrome c Group; D015342:DNA Probes; D045322:Photosynthetic Reaction Center Complex Proteins; C083951:cytochrome c553; C022302:cytochrome C-552; D009572:Nitrite Reductases