转录因子CcmR调控蓝细菌碳浓缩机制的结构生物学基础

Cyanobacterium is an ideal model for studying the photosynthesis and CO2-concentration mechanism (CCM). The transcriptional factor CcmR was first identified in the cyanobacterium Synechocystis sp. PCC6803. It serves as a global controller to increase the expression of CCM related genes, which are suppressed at a high Ci concentration, thus augmenting the uptake of CO2 for the efficacy photosynthesis. Based on our previously determined crystal structure of the apo-form CcmR tetramer, we will systematically investigate the interactions of CcmR with the putative allosteric molecule and its binding DNA, by combining the methodologies of bioinformatics, biochemistry, molecular biology and structural biology. The findings will enable us to elucidate the CcmR allosteric mechanism, and to identify the gene network under the control of CcmR. This project will provide insights into the CCM regulated by CcmR, and might be helpful for guiding the ecological balance control and agricultural production in the future.

蓝细菌是被广泛用于光合作用和碳浓缩机制(CO2-concentrating mechanism, CCM)研究的重要模式生物。CcmR是集胞藻PCC6803中的一个调控碳浓缩机制的全局性转录因子，在低碳信号下解除对CCM相关基因的抑制，引起表达上调，促进CO2的吸收，保证光合作用的顺利进行。我们将以CcmR apo-form四聚体晶体结构为基础，综合利用生物信息学、生物化学、分子生物学以及结构生物学手段，对CcmR与DNA和/或信号分子的相互作用及其二元和三元晶体结构进行系统研究，以期揭示CcmR的别构机理，并基于CcmR特异性识别的DNA序列鉴定其调控的下游基因网络。该项目将阐明CcmR的调控碳浓缩机制的结构基础，有望为生态平衡和农业生产提供理论指导。

蓝细菌是研究光合作用以及碳氮代谢调控的模式生物。蓝细菌转录因子CcmR（NdhR）是一个全局性调控因子，参与调控碳浓缩机制（CO2-concentrating mechanism, CCM）。我们通过SPR实验，发现集胞藻PCC6803的NdhR结合效应分子2-OG和2-PG。我们解析了全长的NdhR与2-OG以及NdhR的RD domain与2-PG的结构。进一步发现NdhR通过响应2-OG、2-PG的浓度变化进而调控CCM中无机碳转运体的活性，维持蓝细菌体内的碳氮平衡。