Department of Chemistry, Indiana University Bloomington, Indiana, USA.
Department of Biology, Indiana University Bloomington, Indiana, USA.
mBio. 2020 Mar 17;11(2):e03197-19. doi: 10.1128/mBio.03197-19.
A microfluidic system coupled with fluorescence microscopy is a powerful approach for quantitative analysis of bacterial growth. Here, we measure parameters of growth and dynamic localization of the cell division initiation protein FtsZ in Consistent with previous reports, we found that after division, FtsZ rings remain at the cell poles, and polar FtsZ ring disassembly coincides with rapid Z-ring accumulation at the midcell. In cells mutated for , however, the polar FtsZ rings persist indefinitely, suggesting that the primary function of the Min system is in Z-ring disassembly. The inability to recycle FtsZ monomers in the mutant results in the simultaneous maintenance of multiple Z-rings that are restricted by competition for newly synthesized FtsZ. Although the parameters of FtsZ dynamics change in the mutant, the overall cell division time remains the same, albeit with elongated cells necessary to accumulate a critical threshold amount of FtsZ for promoting medial division. Finally, the mutant characteristically produces minicells composed of polar peptidoglycan shown to be inert for remodeling in the wild type. Polar peptidoglycan, however, loses its inert character in the mutant, suggesting that the Min system not only is important for recycling FtsZ but also may have a secondary role in the spatiotemporal regulation of peptidoglycan remodeling. Many bacteria grow and divide by binary fission in which a mother cell divides into two identical daughter cells. To produce two equally sized daughters, the division machinery, guided by FtsZ, must dynamically localize to the midcell each cell cycle. Here, we quantitatively analyzed FtsZ dynamics during growth and found that the Min system of is essential to disassemble FtsZ rings after division. Moreover, a failure to efficiently recycle FtsZ results in an increase in cell size. Finally, we show that the Min system has an additional role in inhibiting cell wall turnover and contributes to the "inert" property of cell walls at the poles.
一种与荧光显微镜相结合的微流控系统是定量分析细菌生长的强大方法。在这里，我们测量了细菌生长参数和细胞分裂起始蛋白 FtsZ 的动态定位。与之前的报告一致，我们发现分裂后，FtsZ 环留在细胞极，极区 FtsZ 环的解体与中隔处 Z 环的快速积累同时发生。然而，在 突变的细胞中，极区 FtsZ 环会无限期地持续存在，这表明 Min 系统的主要功能是在 Z 环解体。在 突变体中，FtsZ 单体无法回收，导致多个 Z 环同时维持，这些 Z 环受到新合成的 FtsZ 竞争的限制。尽管 FtsZ 动力学的参数在 突变体中发生了变化，但总的细胞分裂时间保持不变，尽管细胞伸长以积累促进中部分裂的临界量的 FtsZ。最后， 突变体特征性地产生由极肽聚糖组成的小型细胞，野生型中这些肽聚糖显示出惰性，无法重塑。然而，在 突变体中，极肽聚糖失去了其惰性特征，这表明 Min 系统不仅对 FtsZ 的回收很重要，而且可能在肽聚糖重塑的时空调节中具有次要作用。许多细菌通过二分分裂生长和分裂，其中母细胞分裂成两个相同的子细胞。为了产生两个大小相等的子细胞，由 FtsZ 指导的分裂机制必须在每个细胞周期动态定位到中隔。在这里，我们定量分析了生长过程中的 FtsZ 动力学，发现 的 Min 系统对于分裂后 FtsZ 环的解体是必不可少的。此外，FtsZ 回收效率的降低会导致细胞尺寸增加。最后，我们表明 Min 系统在抑制细胞壁周转方面具有额外的作用，并有助于细胞壁在极区的“惰性”特性。
