CP-47 is absent in a genetically engineered mutant of cyanobacterium Synechocystis 6803, in which the psbB gene [encoding the chlorophyll-binding photosystem II (PSII) protein CP-47] was interrupted. Another chlorophyll-binding PSII protein, CP-43, is present in the mutant, and functionally inactive PSII-enriched particles can be isolated from mutant thylakoids. We interpret these data as indicating that the PSII core complex of the mutant still assembles in the absence of CP-47. The mutant lacks a 77 K fluorescence emission maximum at 695 nm, suggesting that the PSII reaction center is not functional. The absence of primary photochemistry was indicated by EPR and optical measurements: no chlorophyll triplet originating from charge recombination between P680+ and Pheo- was observed in the mutant, and there were no flash-induced absorption changes at 820 nm attributable to chlorphyll P680 oxidation. These observations lead us to conclude that CP-47 plays an essential role in the activity of the PSII reaction center.
|Original language||English (US)|
|Number of pages||4|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - 1986|
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