Abstract: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.
