Mechanism of transcriptional regulation in cyanobacteria upon acclimation to high-light conditions

以前，我们分析了启动子结构的psaAB基因编码的反应中心亚基的光系统I（PSI）的蓝藻集胞藻属PCC 6803。有两个启动子，P1和P2，这两个都表现出典型的高光（HL）响应的PSI基因，他们的活动是高的低光（LL）条件下，但迅速下调后，转移到HL条件。在这项研究中，它表明，反应调节RpaB结合到多个高光调节1（HLR1）序列的上游区域的psaAB基因。我们探讨了顺式元件的调节作用，包括这些HLR1序列对P1和P2的个别活动。我们的研究结果表明，顺式元件，包括多个HLR1序列，不同地调节psaAB基因的双启动子的活动，以实现基因表达的微调。

Previously, we analyzed the promoter architecture of the psaAB genes encoding reaction center subunits of photosystem I (PSI) in the cyanobacterium Synechocystis sp. PCC 6803. There exist two promoters, P1 and P2, both of which show typical high-light (HL) response of PSI genes ; their activities are high under low-light (LL) conditions but rapidly downregulated upon the shift to HL conditions. In this study, it was shown that a response regulator RpaB binds to multiple high-light regulatory 1 (HLR1) sequences in the upstream region of the psaAB genes. We explored the regulatory role of cis-elements, including these HLR1 sequences on the individual activity of P1 and P2. Our results suggest that cis-elements, including multiple HLR1 sequences, differently regulate the activities of dual promoters of the psaAB genes to achieve the fine-tuning of the gene expression.