Campos Manuel, Surovtsev Ivan V, Kato Setsu, Paintdakhi Ahmad, Beltran Bruno, Ebmeier Sarah E, Jacobs-Wagner Christine
Microbial Sciences Institute, Yale University, West Haven, CT 06516, USA; Howard Hughes Medical Institute, Yale University, New Haven, CT 06520, USA.
Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA.
Cell. 2014 Dec 4;159(6):1433-46. doi: 10.1016/j.cell.2014.11.022.
Cell size control is an intrinsic feature of the cell cycle. In bacteria, cell growth and division are thought to be coupled through a cell size threshold. Here, we provide direct experimental evidence disproving the critical size paradigm. Instead, we show through single-cell microscopy and modeling that the evolutionarily distant bacteria Escherichia coli and Caulobacter crescentus achieve cell size homeostasis by growing, on average, the same amount between divisions, irrespective of cell length at birth. This simple mechanism provides a remarkably robust cell size control without the need of being precise, abating size deviations exponentially within a few generations. This size homeostasis mechanism is broadly applicable for symmetric and asymmetric divisions, as well as for different growth rates. Furthermore, our data suggest that constant size extension is implemented at or close to division. Altogether, our findings provide fundamentally distinct governing principles for cell size and cell-cycle control in bacteria.
细胞大小控制是细胞周期的一个内在特征。在细菌中，细胞生长和分裂被认为是通过一个细胞大小阈值耦合在一起的。在此，我们提供了直接的实验证据反驳关键大小范式。相反，我们通过单细胞显微镜观察和建模表明，在进化上距离较远的细菌大肠杆菌和新月柄杆菌通过在每次分裂之间平均生长相同的量来实现细胞大小稳态，而与出生时的细胞长度无关。这种简单的机制提供了一种非常稳健的细胞大小控制，无需精确控制，能在几代之内以指数方式消除大小偏差。这种大小稳态机制广泛适用于对称和不对称分裂以及不同的生长速率。此外，我们的数据表明，恒定的大小扩展是在分裂时或接近分裂时实现的。总之，我们的发现为细菌中的细胞大小和细胞周期控制提供了根本不同的调控原则。
