Abstract
Higher plants have a number of PsbP homologs (PsbP-like proteins: PPLs, PsbP-domein proteins: PPDs) in addition to the authentic PsbP, which regulates the oxygen-evolving reaction in photosystem II (PSII). Among the PsbP homologs, PPL1 is the most homologous protein to a cyanobacterial PsbP (cyanoP), and we previously reported that PPL1 is involved in the repair of photo-damaged PSII under high light condition (Ishihara et al. 2007, Plant Physiol. 145, 668-679). In this study, we characterized another PsbP homolg, PPD3. In co-expression analysis using the ATTED-II program, PPD3 gene showed the expression pattern similar to that of PPL1, indicating that PPD3 might also be involved in the repair of PSII. Characterization of the ppd3 mutant showed that the growth of ppd3 was comparable with that of wild type under both normal and high light conditions, while the expression of PPL1 was up-regulated in the ppd3 mutant. This suggests the functional interaction between PPL1 and PPD3. Further characterization of the PPL1 and PPD3 functions will be reported.
