Ehrle Haley M, Guidry Jacob T, Iacovetto Rebecca, Salisbury Anne K, Sandidge D J, Bowman Grant R
Department of Molecular Biology, University of Wyoming, Laramie, Wyoming, USA.
Department of Molecular Biology, University of Wyoming, Laramie, Wyoming, USA
J Bacteriol. 2017 Aug 8;199(17). doi: 10.1128/JB.00111-17. Print 2017 Sep 1.
Despite being perceived as relatively simple organisms, many bacteria exhibit an impressive degree of subcellular organization. In , the evolutionarily conserved polar organizing protein PopZ facilitates cytoplasmic organization by recruiting chromosome centromeres and regulatory proteins to the cell poles. Here, we characterize the localization and function of PopZ in , a genetically related species with distinct anatomy. In this species, we find that PopZ molecules are relocated from the old pole to the new pole in the minutes following cell division. PopZ is not required for the localization of the histidine kinases DivJ and PdhS1, which become localized to the old pole after PopZ relocation is complete. The histidine kinase PdhS2 is temporally and spatially related to PopZ in that it localizes to transitional poles just before they begin to shed PopZ and disappears from the old pole after PopZ relocalization. At the new pole, PopZ is required for tethering the centromere of at least one of multiple replicons (chromosome I), and the loss of results in a severe chromosome segregation defect, aberrant cell division, and cell mortality. After cell division, the daughter that inherits polar PopZ is shorter in length and delayed in chromosome I segregation compared to its sibling. In this cell type, PopZ completes polar relocation well before the onset of chromosome segregation. While PopZ resembles its homolog in chromosome tethering activity, other aspects of its localization and function indicate distinct properties related to differences in cell organization. Members of the exhibit a wide range of phenotypic diversity despite sharing many conserved genes. In recent years, the extent to which this diversity is reflected at the level of subcellular organization has become increasingly apparent. However, which factors control such organization and how they have changed to suit different body plans are poorly understood. This study focuses on PopZ, which is essential for many aspects of polar organization in , but its role in other species is unclear. We explore the similarities and differences in PopZ functions between and and conclude that PopZ lies at a point of diversification in the mechanisms that control cytoplasmic organization and cell cycle regulation in .
尽管细菌被视为相对简单的生物体，但许多细菌展现出了令人印象深刻的亚细胞组织程度。在[具体物种1]中，进化上保守的极性组织蛋白PopZ通过将染色体着丝粒和调节蛋白招募到细胞极来促进细胞质组织。在这里，我们描述了PopZ在[具体物种2]中的定位和功能，[具体物种2]是一种具有独特结构的遗传相关物种。在这个物种中，我们发现PopZ分子在细胞分裂后的几分钟内从旧极重新定位到新极。组氨酸激酶DivJ和PdhS1的定位不需要PopZ，它们在PopZ重新定位完成后定位到旧极。组氨酸激酶PdhS2在时间和空间上与PopZ相关，因为它在过渡极开始脱落PopZ之前定位到过渡极，并在PopZ重新定位后从旧极消失。在新极，PopZ是将多个复制子（染色体I）中至少一个的着丝粒系留在新极所必需的，PopZ的缺失会导致严重的染色体分离缺陷、异常细胞分裂和细胞死亡。细胞分裂后，继承极性PopZ的子代与其同胞相比，长度较短且染色体I分离延迟。在这种细胞类型中，PopZ在染色体分离开始之前就很好地完成了极性重新定位。虽然[具体物种2]的PopZ在染色体系留活性方面类似于其[具体物种1]的同源物，但其定位和功能的其他方面表明与细胞组织差异相关的不同特性。[具体物种2]的成员尽管共享许多保守基因，但表现出广泛的表型多样性。近年来，这种多样性在亚细胞组织水平上的体现程度越来越明显。然而，哪些因素控制这种组织以及它们如何变化以适应不同的身体结构却知之甚少。本研究聚焦于PopZ，它对[具体物种2]中极性组织的许多方面至关重要，但其在其他物种中的作用尚不清楚。我们探讨了[具体物种1]和[具体物种2]之间PopZ功能的异同，并得出结论，PopZ处于控制[具体物种2]细胞质组织和细胞周期调控机制的多样化点上。
