Marczynski Gregory T, Petit Kenny, Patel Priya
Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada.
Front Microbiol. 2019 Feb 26;10:279. doi: 10.3389/fmicb.2019.00279. eCollection 2019.
Despite much effort, the bacterial cell cycle has proved difficult to study and understand. Bacteria do not conform to the standard eukaryotic model of sequential cell-cycle phases. Instead, for example, bacteria overlap their phases of chromosome replication and chromosome partitioning. In "eukaryotic terms," bacteria simultaneously perform "S-phase" and "mitosis" whose coordination is absolutely required for rapid growth and survival. In this review, we focus on the signaling "crosstalk," meaning the signaling mechanisms that advantageously commit bacteria to start both chromosome replication and chromosome partitioning. After briefly reviewing the molecular mechanisms of replication and partitioning, we highlight the crosstalk research from , and . As the initiator of chromosome replication, DnaA also mediates crosstalk in each of these model bacteria but not always in the same way. We next focus on the cell cycle and describe how it is revealing novel crosstalk mechanisms. Recent experiments show that the novel nucleoid associated protein GapR has a special role(s) in starting and separating the replicating chromosomes, so that upon asymmetric cell division, the new chromosomes acquire different fates in 's distinct replicating and non-replicating cell types. The PopZ protein forms a special cell-pole organizing matrix that anchors the chromosomes through their centromere-like DNA sequences near the origin of replication. We also describe how PopZ anchors and interacts with several key cell-cycle regulators, thereby providing an organized subcellular environment for more novel crosstalk mechanisms.
尽管付出了诸多努力，但细菌的细胞周期已被证明难以研究和理解。细菌并不符合真核细胞连续细胞周期阶段的标准模式。例如，细菌的染色体复制和染色体分配阶段相互重叠。用“真核生物的术语”来说，细菌同时进行“ S期”和“有丝分裂”，其协调对于快速生长和存活绝对必要。在本综述中，我们聚焦于信号“串扰”，即那些有利于促使细菌启动染色体复制和染色体分配的信号传导机制。在简要回顾复制和分配的分子机制后，我们着重介绍来自[具体研究对象1]、[具体研究对象2]和[具体研究对象3]的串扰研究。作为染色体复制的起始因子，DnaA在这些模式细菌中均介导串扰，但方式并不总是相同。接下来，我们聚焦于[具体细菌名称]的细胞周期，并描述其如何揭示新的串扰机制。最近的实验表明，新型类核相关蛋白GapR在启动和分离复制中的染色体方面具有特殊作用，因此在不对称细胞分裂时，新染色体在[具体细菌名称]不同的复制和非复制细胞类型中获得不同的命运。[具体细菌名称]的PopZ蛋白形成一种特殊的细胞极组织基质，通过其在复制起点附近类似着丝粒的DNA序列锚定染色体。我们还描述了PopZ如何锚定并与几种关键的细胞周期调节因子相互作用，从而为更多新的串扰机制提供一个有组织的亚细胞环境。
