Cell division is tightly controlled in space and time to maintain cell size and ploidy within narrow bounds. In bacteria, the canonical Minicell (Min) and nucleoid occlusion (Noc) systems together ensure that division is restricted to midcell after completion of chromosome segregation¹. It is unknown how division site selection is controlled in bacteria that lack homologues of the Min and Noc proteins, including mycobacteria responsible for tuberculosis and other chronic infections². Here, we use correlated optical and atomic-force microscopy^3,4 to demonstrate that morphological landmarks (waveform troughs) on the undulating surface of mycobacterial cells correspond to future sites of cell division. Newborn cells inherit wave troughs from the (grand)mother cell and ultimately divide at the centre-most wave trough, making these morphological features the earliest known landmark of future division sites. In cells lacking the chromosome partitioning (Par) system, missegregation of chromosomes is accompanied by asymmetric cell division at off-centre wave troughs, resulting in the formation of anucleate cells. These results demonstrate that inherited morphological landmarks and chromosome positioning together restrict mycobacterial division to the midcell position.

中文翻译：

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分枝部位的选择与分枝杆菌中遗传的细胞表面波谷有关。

细胞分裂的空间和时间受到严格控制，以将细胞大小和倍性维持在狭窄的范围内。在细菌中，规范的小细胞（最小）和核苷闭塞（Noc）系统共同确保在染色体分离¹完成后，分裂仅限于中细胞。尚不清楚在缺乏Min和Noc蛋白同源物的细菌（包括负责结核病和其他慢性感染^2的分枝杆菌）中如何控制分裂位点的选择。在这里，我们使用相关的光学和原子力显微镜^3,4证明分枝杆菌细胞起伏表面上的形态学标志（波形谷）对应于将来的细胞分裂位点。新生细胞继承了（大）母细胞的波谷，并最终在最中心的波谷处分裂，使这些形态特征成为未来分裂位点的最早已知地标。在缺乏染色体分区（Par）系统的细胞中，染色体的偏析伴随着偏心波谷处细胞的不对称分裂，从而导致无核细胞的形成。这些结果表明，继承的形态学标志和染色体定位一起将分枝杆菌分裂限制在中细胞位置。