Temporal changes in cold-inducible and uncharacterized Csps under heat and oxidative stress signify a role in bacterial stress response and adaptation
摘要
E. coli has a family of nine homologous cold shock proteins (Csps) of which few members are considered stress proteins. Even with high sequence and structural similarity, not all Csps are expressed after a cold shock, and some are not even considered true Csps. Their designation of “cold shock proteins” is therefore misleading. Understanding their roles could shed light on the necessity of multiple Csps in a single bacterium. This study aims to decipher their expression pattern and understand their probable stress-induced functional roles. We analyzed the transcript abundance of csps in response to conditions of nutrients and stresses of cold, heat, and oxidative. The observations revealed diverse induction patterns, with most stresses inducing the uncharacterized and cold-inducible group. In terms of growth in nutrient media, cspA, cspC, cspD, and cspE have varying induction patterns under a rich and minimal medium, while other csps have a stable expression over the growth phases. In response to cold, along with the cold-inducible group, cspF, and cspH are induced whereas cspC, cspD, and cspE do not have a drastic induction pattern. The cspD, cspH, and cspB are particularly upregulated in response to heat, while the levels of cspC decrease over time. Additionally, exposure to 10mM H2O2 significantly upregulated cspA, cspF, and cspI at 15 min and, along with them, cspC, cspE, and cspH at 30 min. In conclusion, this article describes the novel stress induction pattern of all csps and lays emphasis on cspF and cspH that are still to be assigned a functional role. Therefore, though structurally similar, Csps are differentially expressed and could have stress-induced functional roles within the stress response network of E. coli.
Graphical abstract