Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, USA.
John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02134, USA; Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02134, USA.
Cell Rep. 2022 Mar 22;38(12):110539. doi: 10.1016/j.celrep.2022.110539.
Escherichia coli cell cycle features two critical cell-cycle checkpoints: initiation of replication and the onset of constriction. While the initiation of DNA replication has been extensively studied, it is less clear what triggers the onset of constriction and when exactly it occurs during the cell cycle. Here, using high-throughput fluorescence microscopy in microfluidic devices, we determine the timing for the onset of constriction relative to the replication cycle in different growth rates. Our single-cell data and modeling indicate that the initiation of constriction is coupled to replication-related processes in slow growth conditions. Furthermore, our data suggest that this coupling involves the mid-cell chromosome blocking the onset of constriction via some form of nucleoid occlusion occurring independently of SlmA and the Ter linkage proteins. This work highlights the coupling between replication and division cycles and brings up a new nucleoid mediated control mechanism in E. coli.
复制的起始和收缩的开始。虽然 DNA 复制的起始已经被广泛研究，但触发收缩开始的原因以及它在细胞周期中何时发生还不太清楚。在这里，我们使用微流控装置中的高通量荧光显微镜，确定了在不同生长速率下，相对于复制周期，收缩开始的时间。我们的单细胞数据和模型表明，在缓慢的生长条件下，收缩的开始与与复制相关的过程偶联。此外，我们的数据表明，这种偶联涉及到通过某种形式的核区遮挡，使中体染色体阻止收缩的开始，而这种核区遮挡与 SlmA 和 Ter 连接蛋白无关。这项工作强调了复制和分裂周期之间的耦合，并提出了大肠杆菌中一种新的核区介导的控制机制。
