Division of Biological Sciences, University of Missouri, Columbia, MO, 65203, USA.
Department of Molecular Biology, Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden.
Mol Microbiol. 2019 Apr;111(4):1074-1092. doi: 10.1111/mmi.14212. Epub 2019 Mar 4.
The mechanisms that restrict peptidoglycan biosynthesis to the pole during elongation and re-direct peptidoglycan biosynthesis to mid-cell during cell division in polar-growing Alphaproteobacteria are largely unknown. Here, we explore the role of early division proteins of Agrobacterium tumefaciens including three FtsZ homologs, FtsA and FtsW in the transition from polar growth to mid-cell growth and ultimately cell division. Although two of the three FtsZ homologs localize to mid-cell, exhibit GTPase activity and form co-polymers, only one, FtsZ , is required for cell division. We find that FtsZ is required not only for constriction and cell separation, but also for initiation of peptidoglycan synthesis at mid-cell and cessation of polar peptidoglycan biosynthesis. Depletion of FtsZ in A. tumefaciens causes a striking phenotype: cells are extensively branched and accumulate growth active poles through tip splitting events. When cell division is blocked at a later stage by depletion of FtsA or FtsW, polar growth is terminated and ectopic growth poles emerge from mid-cell. Overall, this work suggests that A. tumefaciens FtsZ makes distinct contributions to the regulation of polar growth and cell division.
在伸长过程中将肽聚糖生物合成限制在极处，并且在极性生长的α变形菌中在细胞分裂期间将肽聚糖生物合成重新引导到中央细胞的机制在很大程度上是未知的。在这里，我们探索了根瘤农杆菌的早期分裂蛋白（包括三个 FtsZ 同源物、FtsA 和 FtsW）在从极生长到中央细胞生长的转变以及最终细胞分裂中的作用。尽管三个 FtsZ 同源物中的两个定位于中央细胞，表现出 GTPase 活性并形成共聚物，但只有一个，FtsZ，是细胞分裂所必需的。我们发现 FtsZ 不仅需要收缩和细胞分离，还需要在中央细胞开始肽聚糖合成并停止极肽聚糖生物合成。根瘤农杆菌中 FtsZ 的耗竭会导致明显的表型：细胞广泛分支，并通过尖端分裂事件积累生长活跃的极。当 FtsA 或 FtsW 的耗竭在后期阻止细胞分裂时，极生长终止，并且从中央细胞出现异位生长极。总的来说，这项工作表明根瘤农杆菌 FtsZ 对极性生长和细胞分裂的调节有不同的贡献。
