The proteolytic degradation of the photodamaged D1 core subunit during the photosystemⅡ(PSⅡ)repair cycle is well understood,but chlorophyll turnover during D1 degradation remains unclear.Here,we report that Arabidop...The proteolytic degradation of the photodamaged D1 core subunit during the photosystemⅡ(PSⅡ)repair cycle is well understood,but chlorophyll turnover during D1 degradation remains unclear.Here,we report that Arabidopsis thaliana CHLOROPHYLLASE 1(CLH1)plays important roles in the PSII repair process.The abundance of CLH1 and CLH2 peaks in young leaves and is induced by high-light exposure.Seedlings of clh1 single and clh1-1/2-2 double mutants display increased photoinhibition after long-term high-light exposure,whereas seedlings overexpressing CLH1 have enhanced light tolerance compared with the wild type.CLH1 is localized in the developing chloroplasts of young leaves and associates with the PSⅡ-dismantling complexes RCC1 and RC47,with a preference for the latter upon exposure to high light.Furthermore,degradation of damaged D1 protein is retarded in young clh1-1/2-2 leaves after 18-h highlight exposure but is rescued by the addition of recombinant CLH1 in vitro.Moreover,overexpression of CLH1 in a variegated mutant(var2~2)that lacks thylakoid protease FtsH2,with which CLH1 interacts,suppresses the variegation and restores D1 degradation.A var2-2 clh1-1/2-2triple mutant shows more severe variegation and seedling death.Taken together,these results establish CLH1 as a long-sought chlorophyll dephytylation enzyme that is involved in PSⅡrepair and functions in long-term adaptation of young leaves to high-light exposure by facilitating FtsH-mediated D1 degradation.展开更多
基金the National Natural Science Foundation of China,People's Republic of China(grant nos.31272214 and 31171988)the National Key Basic Research Program of China,People's Republic of China(grant no.2013CB127105).
文摘The proteolytic degradation of the photodamaged D1 core subunit during the photosystemⅡ(PSⅡ)repair cycle is well understood,but chlorophyll turnover during D1 degradation remains unclear.Here,we report that Arabidopsis thaliana CHLOROPHYLLASE 1(CLH1)plays important roles in the PSII repair process.The abundance of CLH1 and CLH2 peaks in young leaves and is induced by high-light exposure.Seedlings of clh1 single and clh1-1/2-2 double mutants display increased photoinhibition after long-term high-light exposure,whereas seedlings overexpressing CLH1 have enhanced light tolerance compared with the wild type.CLH1 is localized in the developing chloroplasts of young leaves and associates with the PSⅡ-dismantling complexes RCC1 and RC47,with a preference for the latter upon exposure to high light.Furthermore,degradation of damaged D1 protein is retarded in young clh1-1/2-2 leaves after 18-h highlight exposure but is rescued by the addition of recombinant CLH1 in vitro.Moreover,overexpression of CLH1 in a variegated mutant(var2~2)that lacks thylakoid protease FtsH2,with which CLH1 interacts,suppresses the variegation and restores D1 degradation.A var2-2 clh1-1/2-2triple mutant shows more severe variegation and seedling death.Taken together,these results establish CLH1 as a long-sought chlorophyll dephytylation enzyme that is involved in PSⅡrepair and functions in long-term adaptation of young leaves to high-light exposure by facilitating FtsH-mediated D1 degradation.
