Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, NE2 4AX, UK.
Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Van Der Maasweg 9, Delft, 2629 HZ, The Netherlands.
Nat Commun. 2021 Apr 27;12(1):2448. doi: 10.1038/s41467-021-22526-0.
Despite the central role of division in bacterial physiology, how division proteins work together as a nanoscale machine to divide the cell remains poorly understood. Cell division by cell wall synthesis proteins is guided by the cytoskeleton protein FtsZ, which assembles at mid-cell as a dense Z-ring formed of treadmilling filaments. However, although FtsZ treadmilling is essential for cell division, the function of FtsZ treadmilling remains unclear. Here, we systematically resolve the function of FtsZ treadmilling across each stage of division in the Gram-positive model organism Bacillus subtilis using a combination of nanofabrication, advanced microscopy, and microfluidics to measure the division-protein dynamics in live cells with ultrahigh sensitivity. We find that FtsZ treadmilling has two essential functions: mediating condensation of diffuse FtsZ filaments into a dense Z-ring, and initiating constriction by guiding septal cell wall synthesis. After constriction initiation, FtsZ treadmilling has a dispensable function in accelerating septal constriction rate. Our results show that FtsZ treadmilling is critical for assembling and initiating the bacterial cell division machine.
尽管分裂在细菌生理学中起着核心作用，但分裂蛋白如何作为一个纳米级机器协同工作以分裂细胞仍然知之甚少。细胞壁合成蛋白的细胞分裂由细胞骨架蛋白 FtsZ 指导，FtsZ 在细胞中部组装成由 treadmilling 丝组成的密集 Z 环。然而，尽管 FtsZ treadmilling 对于细胞分裂是必不可少的，但 FtsZ treadmilling 的功能仍然不清楚。在这里，我们使用纳米制造、高级显微镜和微流控技术的组合，通过超高灵敏度测量活细胞中分裂蛋白的动力学，系统地解析了革兰氏阳性模式生物枯草芽孢杆菌在每个分裂阶段的 FtsZ treadmilling 功能。我们发现 FtsZ treadmilling 具有两个重要功能：介导弥散的 FtsZ 丝凝聚成密集的 Z 环，以及通过引导隔膜细胞壁合成来启动收缩。收缩启动后，FtsZ treadmilling 在加速隔膜收缩率方面具有非必需的功能。我们的结果表明，FtsZ treadmilling 对于组装和启动细菌细胞分裂机器至关重要。
