集胞藻PCC6803响应铜浓度与光照双重变化的CopRS信号转导机制研究

光和铜都是蓝藻光合作用所必需，可一旦过量会严重损伤细胞，因此细胞的响应和调控非常重要。模式生物集胞藻PCC6803的CopRS二元信号转导系统能够响应光照和铜浓度变化，编码该系统的两个操纵子拷贝序列相似且分别位于核基因组与质粒。可是两个重要环境因子为什么用一个系统来响应调控？为何要两套操纵子？新研究表明铜在光合作用能量过程有重要作用，本项目猜想CopRS系统响应调控铜和光是相互协同的，非线性的复杂调控需要两套操纵子才能完成。基于此假说，本研究通过构建阻断CopRS铜浓度调节能力的双突变株系和监测不同光照下胞内铜浓度变化来验证协同性，通过特定条件下比较野生株和单操纵子突变株验证双操纵子的必要性，通过建立数学模型阐释CopRS如何精密完成光铜双因子的协同调控。本研究不仅对解析原核藻类适应复杂环境的机理有深刻的理论意义，而且在蓝藻藻华防控和经济蓝藻培养方面有潜在的应用前景。

Light and copper are required for cyanobacterial photosynthesis but detrimental if excessive to the cell, therefore the response and regulation are important. The CopRS two-component signal transduction system of model organism Synechocystis sp. PCC 6803 is able to respond to the changes in light intensities and copper concentrations. Two operon copies coding this system are located in the chromosomal and a plasmid respectively. However, why are the two vital environmental factors responded and regulated by such a single system? And why are there two operon copies required? A recent study has suggested that copper plays a key role in the energy metabolism of photosynthesis. Here we hypothesize that the response-regulations to light and copper by the CopRS system are synergic, and two operon copies are required because of the non-linear complex regulations. To prove it, this study plans to testify the relatedness by constructing a double mutant disabling the copper regulation by the CopRS; to testify the necessity of the dual operons by comparing single-operon mutants with the wild type strain; to elucidate the synergy by mathematic modeling. This study will show not only its profound scientific significance on understanding the mechanism of prokaryotic cyanobacterial adaptation to a complex environment but also its potential application in controlling cyanobacterial blooms and culturing economic cyanobacteria.