Bending forces plastically deform growing bacterial cell walls
Bending forces plastically deform growing bacterial cell walls
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DOI：
10.1073/pnas.1317497111
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发表时间：
2014-04-22
影响因子：
11.1
通讯作者：
Jun, Suckjoon
中科院分区：
文献类型：
--
作者：
Amir, Ariel;Babaeipour, Farinaz;Jun, Suckjoon
细胞壁决定了细菌中细胞的形状。墙是刚性的，以抵抗大的内部压力，但显着的塑性，以适应广泛的外力和几何约束。目前，尚不清楚细菌是如何保持其形状的。在本文中，我们开发的实验和理论方法，并表明，机械应力调节细菌细胞壁的生长。通过施加一个精确可控的水动力生长杆状大肠杆菌和枯草芽孢杆菌细胞，我们证明了细胞可以表现出两种根本不同的变形模式。当受到瞬时力时，细胞表现得像弹性杆，但当施加力时发生显著的细胞壁合成时，细胞发生塑性变形。变形的细胞总能恢复形状。实验结果与位错介导生长理论的预测定量一致。特别是，我们发现，一个单一的无量纲参数，这取决于一个独立测量的物理性质的细胞的组合，可以描述在各种实验条件下的细胞的反应。这些发现提供了对活细胞如何在不同的物理环境下保持其形状的深入了解。
Cell walls define a cell's shape in bacteria. The walls are rigid to resist large internal pressures, but remarkably plastic to adapt to a wide range of external forces and geometric constraints. Currently, it is unknown how bacteria maintain their shape. In this paper, we develop experimental and theoretical approaches and show that mechanical stresses regulate bacterial cell wall growth. By applying a precisely controllable hydrodynamic force to growing rod-shaped Escherichia coli and Bacillus subtilis cells, we demonstrate that the cells can exhibit two fundamentally different modes of deformation. The cells behave like elastic rods when subjected to transient forces, but deform plastically when significant cell wall synthesis occurs while the force is applied. The deformed cells always recover their shape. The experimental results are in quantitative agreement with the predictions of the theory of dislocation-mediated growth. In particular, we find that a single dimensionless parameter, which depends on a combination of independently measured physical properties of the cell, can describe the cell's responses under various experimental conditions. These findings provide insight into how living cells robustly maintain their shape under varying physical environments.