Functional Analysis of PsbP-Like Protein 1 (PPL1) in Arabidopsis

摘要

Higher plants have a number of PsbP homologs (PsbPlike proteins: PPLs, PsbP-domain proteins: PPDs) in addition to the authentic PsbP in the oxygen-evolving complex of Photosystem Ⅱ (PSⅡ). Among the PsbP homologs, the PPL1 protein is most homologous to a cyanobacterial PsbP (cyanoP), and we previously reported that PPL1 is required for the efficient repair of photo-damaged PSⅡ under high light conditions [Ishihara et al. (2007) Plant Physiol. 145: 668-679]. However, functional role of PPL1 in the PSⅡ repair cycle has not been clarified yet. In this study, we further investigated molecular function of PPL 1 by characterizing the phenotypes of the PPL1 knockdown plants (pplli) in which PPL1 expressions were differently suppressed. Although growth of the pplli mutants under low intensity light was comparable with that of wild type plants, PSⅡ activity of the pplli mutants was more sensitive to high intensity light and the extent of photoinhibition was correlated with the levels of the knocked-down PPL1. The possible functional role of PPL 1 in PSⅡ repair is discussed.