Photosystem II characteristics of a constructed Synechocystis 6803 mutant lacking synthesis of the D1 polypeptide.

Photosystem II (PSII) composition was studied in a mutant of the cyanobacterium Synechosystis 6803 in which synthesis of the reaction center polypeptide D1 has been inactivated. The mutant thylakoids had lost also the other reaction center polypeptide D2 and the chlorophyll alpha-binding protein CP47. Cytochrome b559 and the chlorophyll alpha-binding protein CP43 accumulated to almost wild-type amounts in mutant thylakoids. Also the 33 kDa polypeptide involved in water oxidation was present and membrane-bound in mutant thylakoids. The intrinsic 22 kDa polypeptide, so far known only from plants, was detected both in wild-type and mutant thylakoids.