Laboratoire de Chimie Bactérienne, UMR 7283, IMM, CNRS, Aix Marseille Univ, 31 Chemin Joseph Aiguier, 13009, Marseille, France.
Protein Expression Facility, IMM, CNRS, Aix Marseille Univ, 31 Chemin Joseph Aiguier, 13009, Marseille, France.
Sci Rep. 2018 Jan 26;8(1):1660. doi: 10.1038/s41598-018-20145-2.
The activity of the PrkC protein kinase is regulated in a sophisticated manner in Bacillus subtilis cells. In spores, in the presence of muropeptides, PrkC stimulates dormancy exit. The extracellular region containing PASTA domains binds peptidoglycan fragments to probably enhance the intracellular kinase activity. During exponential growth, the cell division protein GpsB interacts with the intracellular domain of PrkC to stimulate its activity. In this paper, we have reinvestigated the regulation of PrkC during exponential and stationary phases. We observed that, during exponential growth, neither its septal localization nor its activity are influenced by the addition of peptidoglycan fragments or by the deletion of one or all PASTA domains. However, Dynamic Light Scattering experiments suggest that peptidoglycan fragments bind specifically to PrkC and induce its oligomerization. In addition, during stationary phase, PrkC appeared evenly distributed in the cell wall and the deletion of one or all PASTA domains led to a non-activated kinase. We conclude that PrkC activation is not as straightforward as previously suggested and that regulation of its kinase activity via the PASTA domains and peptidoglycan fragments binding occurs when PrkC is not concentrated to the bacterial septum, but all over the cell wall in non-dividing bacillus cells.
枯草芽孢杆菌细胞中 PrkC 蛋白激酶的活性受到精细调控。在芽孢中，存在肽聚糖的情况下，PrkC 会刺激休眠退出。含有 PASTA 结构域的细胞外区域结合肽聚糖片段，可能会增强细胞内激酶的活性。在指数生长期，细胞分裂蛋白 GpsB 与 PrkC 的细胞内结构域相互作用，刺激其活性。在本文中，我们重新研究了 PrkC 在指数生长期和静止期的调控。我们观察到，在指数生长期，添加肽聚糖片段或缺失一个或所有 PASTA 结构域既不会影响 PrkC 的隔膜定位，也不会影响其活性。然而，动态光散射实验表明，肽聚糖片段特异性结合 PrkC 并诱导其寡聚化。此外，在静止期，PrkC 均匀分布在细胞壁中，缺失一个或所有 PASTA 结构域会导致激酶失活。我们的结论是，PrkC 的激活并不像之前所认为的那样简单，其激酶活性的调节是通过 PASTA 结构域和肽聚糖片段的结合来实现的，当 PrkC 没有集中到细菌隔膜上时，而是分布在整个非分裂的芽孢细胞壁上。
