A Parallel Adder Coordinates Mycobacterial Cell-Cycle Progression and Cell-Size Homeostasis in the Context of Asymmetric Growth and Organization.
A Parallel Adder Coordinates Mycobacterial Cell-Cycle Progression and Cell-Size Homeostasis in the Context of Asymmetric Growth and Organization.
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DOI：
10.1016/j.cub.2017.09.046
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发表时间：
2017-11-06
期刊：
影响因子：
--
通讯作者：
Aldridge BB
中科院分区：
文献类型：
--
作者：
Logsdon MM;Ho PY;Papavinasasundaram K;Richardson K;Cokol M;Sassetti CM;Amir A;Aldridge BB
在模式菌中，如E. coli和B.枯草芽孢杆菌，细胞周期进程和细胞组织的调节实现了细胞大小，复制动力学和染色体定位的一致性。分枝杆菌伸长和分裂不对称，引起密切相关的细胞之间的细胞大小和伸长速率的显着变化。鉴于分枝杆菌的物理不对称性，描述模型细菌中细胞组织和细胞周期进程协调的模型不能直接翻译。在这里，我们使用延时显微镜和荧光报告的DNA复制和染色体定位，以检查协调的生长，分裂和染色体动力学在单细胞水平的耻垢分枝杆菌（M。耻垢病）和牛分枝杆菌卡介苗（BCG）。通过分析染色体和复制体定位，我们证明了染色体定位是不对称的，并与细胞大小成正比。此外，我们发现，细胞的不对称性是保持在整个细胞周期，并没有建立在分裂。使用测量和随机建模的分枝杆菌细胞大小和周期的时间在缓慢和快速的生长条件下，我们发现，充分研究的细胞大小控制模型是不足以解释分枝杆菌细胞周期。相反，我们表明，分枝杆菌细胞周期的进展是由一个前所未有的机制，涉及平行加法器（即恒定的生长增量），开始在复制启动。总之，这些加法器使分枝杆菌种群能够在不同的环境中调节细胞大小，生长和异质性。Logsdon等人研究了不对称生长分枝杆菌的细胞周期动力学，并展示了细胞周期、染色体组织和分裂在单细胞中是如何协调的。一个并行加法器模型，其中细胞增加一个恒定的长度之间的启动和启动分裂，描述细胞大小控制在M。斯美拉和卡介苗。
In model bacteria, such as E. coli and B. subtilis, regulation of cell cycle progression and cellular organization achieves consistency in cell size, replication dynamics, and chromosome positioning. Mycobacteria elongate and divide asymmetrically, giving rise to significant variation in cell size and elongation rate among closely related cells. Given the physical asymmetry of mycobacteria, the models that describe coordination of cellular organization and cell cycle progression in model bacteria are not directly translatable. Here we used time-lapse microscopy and fluorescent reporters of DNA replication and chromosome positioning to examine the coordination of growth, division, and chromosome dynamics at a single-cell level in Mycobacterium smegmatis (M. smegmatis) and Mycobacterium bovis Bacillus Calmette–Guérin (BCG). By analyzing chromosome and replisome localization, we demonstrated that chromosome positioning is asymmetric and proportional to cell size. Furthermore, we found that cellular asymmetry is maintained throughout the cell cycle and is not established at division. Using measurements and stochastic modeling of mycobacterial cell size and cycle timing in both slow and fast growth conditions, we found that well-studied cell size control models are insufficient to explain the mycobacterial cell cycle. Instead, we showed that mycobacterial cell cycle progression is regulated by an unprecedented mechanism involving parallel adders (i.e. constant growth increments) that start at replication initiation. Together, these adders enable mycobacterial populations to regulate cell size, growth, and heterogeneity in the face of varying environments. Logsdon et al. study cell cycle dynamics of asymmetrically growing mycobacteria and show how cell cycle, chromosome organization, and division are coordinated in single cells. A parallel adder model, where cells add a constant length between initiations and initiation to division, describes cell size control in M. smegmatis and BCG.
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影响因子：
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DOI：
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发表时间：
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期刊：
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DOI：
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发表时间：
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影响因子：
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