Buss Jackson, Coltharp Carla, Shtengel Gleb, Yang Xinxing, Hess Harald, Xiao Jie
Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America.
Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia, United States of America.
PLoS Genet. 2015 Apr 7;11(4):e1005128. doi: 10.1371/journal.pgen.1005128. eCollection 2015 Apr.
The prokaryotic tubulin homolog, FtsZ, forms a ring-like structure (FtsZ-ring) at midcell. The FtsZ-ring establishes the division plane and enables the assembly of the macromolecular division machinery (divisome). Although many molecular components of the divisome have been identified and their interactions extensively characterized, the spatial organization of these proteins within the divisome is unclear. Consequently, the physical mechanisms that drive divisome assembly, maintenance, and constriction remain elusive. Here we applied single-molecule based superresolution imaging, combined with genetic and biophysical investigations, to reveal the spatial organization of cellular structures formed by four important divisome proteins in E. coli: FtsZ, ZapA, ZapB and MatP. We show that these interacting proteins are arranged into a multi-layered protein network extending from the cell membrane to the chromosome, each with unique structural and dynamic properties. Further, we find that this protein network stabilizes the FtsZ-ring, and unexpectedly, slows down cell constriction, suggesting a new, unrecognized role for this network in bacterial cell division. Our results provide new insight into the structure and function of the divisome, and highlight the importance of coordinated cell constriction and chromosome segregation.
原核微管同源物FtsZ在细胞中部形成环状结构（FtsZ环）。FtsZ环确定分裂平面，并使大分子分裂机器（分裂体）得以组装。尽管已经鉴定出分裂体的许多分子成分，并对它们的相互作用进行了广泛表征，但这些蛋白质在分裂体内的空间组织尚不清楚。因此，驱动分裂体组装、维持和收缩的物理机制仍然难以捉摸。在这里，我们应用基于单分子的超分辨率成像技术，结合遗传学和生物物理学研究，来揭示大肠杆菌中四种重要分裂体蛋白FtsZ、ZapA、ZapB和MatP所形成的细胞结构的空间组织。我们表明，这些相互作用的蛋白质排列成一个从细胞膜延伸到染色体的多层蛋白质网络，每一层都具有独特的结构和动态特性。此外，我们发现这个蛋白质网络稳定FtsZ环，并且出乎意料的是，减缓了细胞收缩，这表明该网络在细菌细胞分裂中具有一个新的、未被认识的作用。我们的结果为分裂体的结构和功能提供了新的见解，并突出了协调细胞收缩和染色体分离的重要性。
