Response of serine/threonine protein kinase SpkC to high temperature stress in Synechocystis sp. PCC 6803

Abstract:

Serine/threonine protein kinases play important roles to sense and transduce signal to cope with external environment. However, functions of many serine/threonine protein kinases in cyanobacteria are still unknown. [Objective] This study aims to explore whether SpkC in Synechocystis sp. PCC 6803 responses to high temperature stress. [Methods] We used the homologous recombination method to construct the spkC gene knockout mutant (ΔspkC), and then compared the growth rate, pigment contents of ΔspkC mutant and the wild strain under high temperature stress. In addition, we detected chlorophyll fluorescence under high temperature stress. Recoveries of ΔspkC and wild strain from high-temperature stress were determined through measuring the growth rate under normal temperature. [Results] Compared with wild type strain, ΔspkC mutant grew slower, and the contents of three photosynthetic pigments (chlorophyll, carotenoid and phycobilin) decreased after high temperature stress at 42℃. The activity of photosynthetic system Ⅱ in ΔspkC decreased more rapidly at 45℃. What's more, ΔspkC strain was not able to recover after high-temperature stress for 5 days; their survival rate was significantly lower than wild-type. [Conclusion] The deletion of spkC led to severe defect response to high-temperature stress in Synechocystis sp. PCC 6803, which suggests that serine/threonine protein kinase SpkC is involved in response processes against high temperature stress.