蓝细菌Synechocystis sp. PCC 6803强光诱导多肽功能及强光适应分子机制的研究

High light-inducible protein (HLIP) family is essential to survival of cyanobacteria during exposure to high light. In order to know more about the functions of HLIP and related regulators pfsR and dspA, transcription start site analysis, iron homeostasis analysis, photo-oxidative stress and physiological and biochemical characterization will be performed on the photosynthetic model organism Synechocystis sp. PCC 6803. Moreover, stains of HLIP and Slr1128 tagged with 9XHis （or HA, c-myc tags) will be used to isolate the HLIP-PS I trimer complex and a novel carotenoid-binding complex at large scale. The identity of the protein components, physiological/biochemical characterization and the spectroscopic characteristics will be determined. The information obtained will further elucidate the function of HLIP,and its relation to photosynthesis and stress responses. The combination of the three research objectives will not only clarify the function of HLIP, but also reveal the molecular mechanisms of survival employed by Synechocystis sp. PCC 6803 during exposure to high light. The research also lays important foundation for developing cyanobacteria for various applications in biofuel and nutriceuticals, as well as for photosynthesis research.

强光诱导多肽(HLIP)是蓝细菌在强光下存活所必需的蛋白质家族。利用光合模式生物蓝藻Synechocystis sp. PCC6803为实验材料，通过转录组起始位点分析、铁稳态上位分析、光氧化胁迫和生理生化分析等方法，以期获得HLIP及相关调控因子pfsR、dspA功能。此外，利用9XHis （或HA, c-myc tags)标记的HLIP 和Slr1128 菌株，大规模分离HLIP-PS I 三聚体和新型胡萝卜素蛋白复合体，并进行蛋白组分鉴定、生理生化特性和光学特性等分析。结果将进一步阐释HLIP功能及其与光合作用和应激反应的相互关系。这三个方面的研究有机结合，不仅有助于解析蓝藻强光诱导多肽的功能还能够揭示蓝藻在强光下的存活的分子机制，并为蓝藻在光合作用的研究、生物能源及保健品开发应用奠定了基础。

强光逆境会导致蓝藻产生一些列的应激反应机制。本研究通过对逆境反应调节子pfsR的研究，明确了pfsR是铁离子平衡的关键调节因子，能够自我调控，pfsRˉ在强光和缺铁胁迫下具有较高的光系统活性。对全局调控因子dspA生理生化及蛋白质组的研究，明确了dspA能够调控PSII相关蛋白的积累，对PSI强光条件下调相关蛋白的表达，激活铁蛋白及一些金属抗性代谢通路。成功提取到新型强光诱导类胡萝卜素蛋白复合体（HLCC），明确了该复合体蛋白是由Slr1128、IsiA、PsaD和HliA/HliB蛋白组成，85%的色素成天是蓝藻叶黄素和玉米黄素，强光和氧化胁迫能够提高各蛋白组分编码基因表达，揭示HLCC可能通过状态转换的机制保护类囊体膜免受过量光氧化胁迫损伤。本项目研究结果对于揭示强光逆境反应机制具有重要的理论意义。