Host: The Japanese Society of Plant Physiologists
Pages 0121
PsbP, an extrinsic subunit of photosystem II (PSII), is a nuclear-encoded protein that optimizes the water-splitting reaction. In addition to PsbP, higher plants have two PsbP-like (PPL) proteins that show significant sequence similarity to a cyanobacterial PsbP homolog (cyanoP); however, the function of PPLs has not yet been elucidated. In this study, we characterized Arabidopsis mutants lacking either of two PPLs, PPL1 and PPL2. In ppl1 mutant plants, PSII activity was sensitive to high-intensity light and the recovery of photoinhibited PSII activity was delayed. On the other hand, the stoichiometric level and activity of the chloroplast NAD(P)H dehydrogenase (NDH) complex in thylakoids were severely decreased in a ppl2 mutant. These results suggest that during endosymbiosis and subsequent gene transfer to the host nucleus, cyanoP from ancient cyanobacteria evolved into PPL1, PPL2, and PsbP, and each of them has a distinct role in photosynthetic electron transfer.
