Department of Molecular Biology, University of Wyoming, Laramie, WY, USA.
Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, USA.
Nat Commun. 2024 Oct 28;15(1):9282. doi: 10.1038/s41467-024-53395-y.
Asymmetric cell division in bacteria is achieved through cell polarization, where regulatory proteins are directed to specific cell poles. In Caulobacter crescentus, both poles contain a membraneless microdomain, established by the polar assembly hub PopZ, through most of the cell cycle, yet many PopZ clients are unipolar and transiently localized. We find that PopZ's interaction with the response regulator CpdR is controlled by phosphorylation, via the histidine kinase CckA. Phosphorylated CpdR does not interact with PopZ and is not localized to cell poles. At poles where CckA acts as a phosphatase, dephosphorylated CpdR binds directly with PopZ and subsequently recruits ClpX, substrates, and other members of a protease complex to the cell pole. We also find that co-recruitment of protease components and substrates to polar microdomains enhances their coordinated activity. This study connects phospho-signaling with polar assembly and the activity of a protease that triggers cell cycle progression and cell differentiation.
细菌中的不对称细胞分裂是通过细胞极化来实现的，在细胞极化过程中，调节蛋白被定向到特定的细胞极。在新月柄杆菌中，两极都含有一个无膜的微区，这个微区由极性组装中心 PopZ 建立，在细胞周期的大部分时间里都是如此，但许多 PopZ 的客户是单极的，并且是瞬时定位的。我们发现，PopZ 与响应调节剂 CpdR 的相互作用受磷酸化控制，通过组氨酸激酶 CckA 进行调控。磷酸化的 CpdR 不与 PopZ 相互作用，也不定位在细胞极。在 CckA 作为磷酸酶起作用的极，去磷酸化的 CpdR 与 PopZ 直接结合，并随后招募 ClpX、底物和蛋白酶复合物的其他成员到细胞极。我们还发现，蛋白酶成分和底物的共同募集到极性微区增强了它们的协调活性。这项研究将磷酸化信号与引发细胞周期进程和细胞分化的蛋白酶的极性组装和活性联系起来。
