Ahmed Yasin M, Bowman Grant R
Department of Molecular Biology, University of Wyoming, Laramie Wyoming 82071.
bioRxiv. 2023 Aug 20:2023.08.19.553945. doi: 10.1101/2023.08.19.553945.
Asymmetric cell division in bacteria is achieved through cell polarization, where regulatory proteins are directed to specific cell poles. Curiously, 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, de-phosphorylated 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 phosphosignaling 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实现的，在细胞极化过程中，调控蛋白被导向特定的细胞极。奇怪的是，在细胞周期的大部分时间里，两个细胞极都包含一个无膜微区，该微区由极性组装中心PopZ建立，然而许多PopZ的作用对象是单极且瞬时定位的。我们发现，PopZ与应答调节蛋白CpdR的相互作用受磷酸化调控，通过组氨酸激酶CckA进行。磷酸化的CpdR不与PopZ相互作用，也不定位于细胞极。在CckA作为磷酸酶发挥作用的细胞极，去磷酸化的CpdR直接与PopZ结合，随后将ClpX、底物及蛋白酶复合体的其他成员招募到细胞极。我们还发现，将蛋白酶组分和底物共同招募到极性微区可增强它们的协同活性。这项研究将磷酸信号传导与极性组装以及触发细胞周期进程和细胞分化的蛋白酶活性联系起来。
