Trophic Mode-Dependent Proteomic Analysis Reveals Functional Significance of Light- Independent Chlorophyll Synthesis in Synechocystis sp. PCC 6803  

作　　者：Longfa Fang Haitao Ge Xiahe Huana Ye Liu Min Lu Jinlong Wang Weiyang Chen Wu Xu Yingchun Wang 

机构地区：[1]State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Road, Beijing 100101, China [2]Department of Chemistry, University of Louisiana at Lafayette, Lafayette, LA 70504, USA [3]These authors contributed equally to this article

出　　处：《Molecular Plant》2017年第1期73-85,共13页分子植物（英文版）

摘　　要：The photosynthetic model organism Synechocystis sp. PCC 6803 can grow in different trophic modes, depending on the availability of light and exogenous organic carbon source. However, how the protein pro- file changes to facilitate the cells differentially propagate in different modes has not been comprehensively investigated. Using isobaric labeling-based quantitative proteomics, we simultaneously identified and quantified 45% Synechocystis proteome across four different trophic modes, i.e., autotrophic, heterotro- phic, photoheterotrophic, and mixotrophic modes. Among the 155 proteins that are differentially expressed across four trophic modes, proteins involved in nitrogen assimilation and light-independent chlorophyll synthesis are dramatically upregulated in the mixotrophic mode, concomitant with a dramatic increase of PII phosphorylation that senses carbon and nitrogen assimilation status. Moreover, functional study us- ing a mutant defective in light-independent chlorophyll synthesis revealed that this pathway is important for chlorophyll accumulation under a cycled light/dark illumination regime, a condition mimicking day/night cycles in certain natural habitats. Collectively, these results provide the most comprehensive information on trophic mode-dependent protein expression in cyanobacterium, and reveal the functional significance of light-independent chlorophyll synthesis in trophic growth.The photosynthetic model organism Synechocystis sp. PCC 6803 can grow in different trophic modes, depending on the availability of light and exogenous organic carbon source. However, how the protein pro- file changes to facilitate the cells differentially propagate in different modes has not been comprehensively investigated. Using isobaric labeling-based quantitative proteomics, we simultaneously identified and quantified 45% Synechocystis proteome across four different trophic modes, i.e., autotrophic, heterotro- phic, photoheterotrophic, and mixotrophic modes. Among the 155 proteins that are differentially expressed across four trophic modes, proteins involved in nitrogen assimilation and light-independent chlorophyll synthesis are dramatically upregulated in the mixotrophic mode, concomitant with a dramatic increase of PII phosphorylation that senses carbon and nitrogen assimilation status. Moreover, functional study us- ing a mutant defective in light-independent chlorophyll synthesis revealed that this pathway is important for chlorophyll accumulation under a cycled light/dark illumination regime, a condition mimicking day/night cycles in certain natural habitats. Collectively, these results provide the most comprehensive information on trophic mode-dependent protein expression in cyanobacterium, and reveal the functional significance of light-independent chlorophyll synthesis in trophic growth.

关 键 词：PROTEOMICS PHOSPHORYLATION SYNECHOCYSTIS light-independent chlorophyll synthesis nitrogenassimilation 

分 类 号：Q94[生物学—植物学]