Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, USA.
Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA.
Nat Commun. 2023 Sep 15;14(1):5710. doi: 10.1038/s41467-023-41487-0.
The timing of cell division, and thus cell size in bacteria, is determined in part by the accumulation dynamics of the protein FtsZ, which forms the septal ring. FtsZ localization depends on membrane-associated Min proteins, which inhibit FtsZ binding to the cell pole membrane. Changes in the relative concentrations of Min proteins can disrupt FtsZ binding to the membrane, which in turn can delay cell division until a certain cell size is reached, in which the dynamics of Min proteins frees the cell membrane long enough to allow FtsZ ring formation. Here, we study the effect of Min proteins relative expression on the dynamics of FtsZ ring formation and cell size in individual Escherichia coli bacteria. Upon inducing overexpression of minE, cell size increases gradually to a new steady-state value. Concurrently, the time required to initiate FtsZ ring formation grows as the size approaches the new steady-state, at which point the ring formation initiates as early as before induction. These results highlight the contribution of Min proteins to cell size control, which may be partially responsible for the size fluctuations observed in bacterial populations, and may clarify how the size difference acquired during asymmetric cell division is offset.
细胞分裂的时间，从而细菌的细胞大小，部分取决于蛋白质 FtsZ 的积累动态，FtsZ 形成隔膜环。FtsZ 的定位取决于膜相关的 Min 蛋白，Min 蛋白抑制 FtsZ 与细胞极膜的结合。Min 蛋白相对浓度的变化会破坏 FtsZ 与膜的结合，这反过来又会延迟细胞分裂，直到达到一定的细胞大小，此时 Min 蛋白的动力学使细胞膜有足够的时间自由形成 FtsZ 环。在这里，我们研究了 Min 蛋白相对表达对单个大肠杆菌中 FtsZ 环形成和细胞大小动力学的影响。在诱导 minE 过表达后，细胞大小逐渐增加到一个新的稳定状态值。同时，形成 FtsZ 环所需的时间随着大小接近新的稳定状态而增加，此时环的形成早在诱导之前就开始了。这些结果突出了 Min 蛋白对细胞大小控制的贡献，这可能部分解释了在细菌群体中观察到的大小波动，并且可能阐明了在不对称细胞分裂过程中获得的大小差异是如何抵消的。
