Molecular Genetics Group, Groningen Biomolecular Sciences and Biotechnology Institute, Centre for Synthetic Biology, University of Groningen, 9747 AG Groningen, The Netherlands.
Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, CH-1015 Lausanne, Switzerland.
Proc Natl Acad Sci U S A. 2017 Jul 18;114(29):E5959-E5968. doi: 10.1073/pnas.1620608114. Epub 2017 Jul 3.
Accurate spatial and temporal positioning of the tubulin-like protein FtsZ is key for proper bacterial cell division. (pneumococcus) is an oval-shaped, symmetrically dividing opportunistic human pathogen lacking the canonical systems for division site control (nucleoid occlusion and the Min-system). Recently, the early division protein MapZ was identified and implicated in pneumococcal division site selection. We show that MapZ is important for proper division plane selection; thus, the question remains as to what drives pneumococcal division site selection. By mapping the cell cycle in detail, we show that directly after replication both chromosomal origin regions localize to the future cell division sites, before FtsZ. Interestingly, Z-ring formation occurs coincidently with initiation of DNA replication. Perturbing the longitudinal chromosomal organization by mutating the condensin SMC, by CRISPR/Cas9-mediated chromosome cutting, or by poisoning DNA decatenation resulted in mistiming of MapZ and FtsZ positioning and subsequent cell elongation. Together, we demonstrate an intimate relationship between DNA replication, chromosome segregation, and division site selection in the pneumococcus, providing a simple way to ensure equally sized daughter cells.
准确的微管样蛋白 FtsZ 的时空定位对于细菌细胞的正确分裂至关重要。肺炎链球菌是一种椭圆形、对称分裂的机会主义人类病原体，缺乏典型的分裂位点控制（核区阻断和 Min 系统）系统。最近，早期分裂蛋白 MapZ 被鉴定出来，并与肺炎链球菌的分裂位点选择有关。我们表明 MapZ 对正确的分裂平面选择很重要；因此，问题仍然是肺炎链球菌的分裂位点选择是由什么驱动的。通过详细绘制细胞周期图，我们表明，在 FtsZ 之前，直接在复制之后，染色体起始区域就定位到未来的细胞分裂位点。有趣的是，Z 环的形成与 DNA 复制的起始同时发生。通过突变凝聚素 SMC、CRISPR/Cas9 介导的染色体切割或毒害 DNA 解连环来破坏纵向染色体组织，导致 MapZ 和 FtsZ 定位和随后的细胞伸长时机错误。总之，我们证明了肺炎链球菌中 DNA 复制、染色体分离和分裂位点选择之间的密切关系，为确保均等大小的子细胞提供了一种简单的方法。
