为考察集胞藻6803中S2P同源蛋白sll0528的功能，应用实时荧光定量PCR技术研究sll0528基因在各种胁迫条件下不同时间点的表达谱变化。结果表明：sll0528在多种胁迫条件下被显著诱导，根据表达谱特点不同可分为以下三组（1）对高光、双氧水、山梨醇和葡萄糖混养等胁迫的响应属于早期响应，表达量诱导上调的峰值出现在0.5 h内，前三者在0.25h分别上调约10、80和100倍，后者在0.5 h上调9倍左右；（2）对高温和低温胁迫的响应属于中期响应，前者在1 h上调30倍，后者在2 h显著上调280倍；（3）对酸和盐胁迫的响应属于后期响应，在6 h分别上调90和190倍。由此推断，sll0528可能在响应多种外界环境胁迫中起到重要作用，在不同的胁迫条件下可能参与了不同的信号转导途径从而诱导表达的峰值出现时间和数量有所不同。本研究结果为进一步探讨sll0528基因在胁迫条件下的生理功能及其作用的分子机制奠定了基础。

To explore the functions of site-2 protease (S2P) homolog sll0528 in Synechocystis sp. PCC 6803, real-time fluorescence quantitative polymerase chain reaction (FQ-PCR) was used to detect the time-course expression profile of sll0528 under multiple stress conditions. The results showed that sll0528 was induced significantly under different stress conditions; however, stress induction patterns were different and could be classified into three groups. The first group included early response, i.e., sll0528 promptly responded to stress conditions such as exposure to high intensity light, hydrogen peroxide, sorbitol, and glucose mixotrophic condition, where maximal induction occurred within 0.5 h. The expression level increased by 10-, 80-, and 100-fold at 0.25 h when induced by high intensity light, hydrogen peroxide, and sorbitol, respectively, whereas glucose mixotrophic condition increased the expression level by approximately 9-fold after 0.5 h of treatment. The second group included mid-stage response, which was induced by low and high temperature. High temperature stress increased the expression level by 30-fold after 1 h of treatment, whereas low temperature stress significantly increased the expression level by 280-fold after 2 h of treatment. The third group included late response induced by acid and salt stress, which increased the expression level by 90- and 190-fold, respectively, after 6 h of treatment. Taken together, it could be inferred that sll0528 in Synechocystissp.PCC 6803 might play an important role in multiple stress responses. Under different stress conditions, this gene might participate in different signal transduction pathways and showed an expression peak at different levels and at different time-points. These results provide fundamental knowledge for further research to characterize the function and mechanisms of sll0528 in stress response.

国家自然科学基金面上项目（31270085）