摘要
Sedoheptulose-l,7-bisphosphatase （SBPase） is a Calvin cycle enzyme and functions in photosynthetic carbon fixation. We found that SBPase was rapidly carbonylated in response to methyl viologen （MV） treatments in detached leaves of Arabidopsis plants. In vitro activity analysis of the purified recombinant SBPase showed that SBPase was car- bonylated by hydroxyl radicals, which led to enzyme inactivation in an H202 dose-dependent manner. To determine the conformity with carbonylation-caused loss in enzymatic activity in response to stresses, we isolated a loss-of-function mutant sbp, which is deficient in SBPase-dependent carbon assimilation and starch biosynthesis, sbp mutant exhibited a severe growth retardation phenotype, especially for the developmental defects in leaves and flowers where SBPASE is highly expressed. The mutation of SBPASE caused growth retardation mainly through inhibition of cell division and ex- pansion, which can be partially rescued by exogenous application of sucrose. Our findings demonstrate that ROS-induced oxidative damage to SBPase affects growth, development, and chloroplast biogenesis in Arabidopsis through inhibiting carbon assimilation efficiency. The data presented here provide a case study that such inactivation of SBPase caused by carbonyl modification may be a kind of adaptation for plants to restrict the operation of the reductive pentose phosphate pathway under stress conditions.
Sedoheptulose-l,7-bisphosphatase （SBPase） is a Calvin cycle enzyme and functions in photosynthetic carbon fixation. We found that SBPase was rapidly carbonylated in response to methyl viologen （MV） treatments in detached leaves of Arabidopsis plants. In vitro activity analysis of the purified recombinant SBPase showed that SBPase was car- bonylated by hydroxyl radicals, which led to enzyme inactivation in an H202 dose-dependent manner. To determine the conformity with carbonylation-caused loss in enzymatic activity in response to stresses, we isolated a loss-of-function mutant sbp, which is deficient in SBPase-dependent carbon assimilation and starch biosynthesis, sbp mutant exhibited a severe growth retardation phenotype, especially for the developmental defects in leaves and flowers where SBPASE is highly expressed. The mutation of SBPASE caused growth retardation mainly through inhibition of cell division and ex- pansion, which can be partially rescued by exogenous application of sucrose. Our findings demonstrate that ROS-induced oxidative damage to SBPase affects growth, development, and chloroplast biogenesis in Arabidopsis through inhibiting carbon assimilation efficiency. The data presented here provide a case study that such inactivation of SBPase caused by carbonyl modification may be a kind of adaptation for plants to restrict the operation of the reductive pentose phosphate pathway under stress conditions.
基金
This research was supported in part by the Ministry of Science and Technology of China，the National Natural Science Foundation of China，the CAS/SAFEA International Partnership Program for Creative Research Teams,and the Bairen Project of Chinese Academy of Sciences
