Biophysics Program, Stanford University, Stanford, CA, 94305, USA.
Department of Bioengineering, Stanford University, Stanford, CA, 94305, USA.
Nat Commun. 2018 Mar 29;9(1):1280. doi: 10.1038/s41467-018-03633-x.
In the rod-shaped bacterium Escherichia coli, the actin-like protein MreB localizes in a curvature-dependent manner and spatially coordinates cell-wall insertion to maintain cell shape, although the molecular mechanism by which cell width is regulated remains unknown. Here we demonstrate that the membrane protein RodZ regulates the biophysical properties of MreB and alters the spatial organization of E. coli cell-wall growth. The relative expression levels of MreB and RodZ change in a manner commensurate with variations in growth rate and cell width, and RodZ systematically alters the curvature-based localization of MreB and cell width in a concentration-dependent manner. We identify MreB mutants that alter the bending properties of MreB filaments in molecular dynamics simulations similar to RodZ binding, and show that these mutants rescue rod-like shape in the absence of RodZ alone or in combination with wild-type MreB. Thus, E. coli can control its shape and dimensions by differentially regulating RodZ and MreB to alter the patterning of cell-wall insertion, highlighting the rich regulatory landscape of cytoskeletal molecular biophysics.
在杆状细菌大肠杆菌中，肌动蛋白样蛋白 MreB 以依赖于弯曲的方式定位，并在空间上协调细胞壁的插入以维持细胞形状，尽管调节细胞宽度的分子机制尚不清楚。在这里，我们证明了膜蛋白 RodZ 调节 MreB 的物理特性，并改变了大肠杆菌细胞壁生长的空间组织。MreB 和 RodZ 的相对表达水平与生长速率和细胞宽度的变化成正比，并且 RodZ 以浓度依赖的方式系统地改变 MreB 的基于弯曲的定位和细胞宽度。我们鉴定出 MreB 突变体，这些突变体在分子动力学模拟中改变了 MreB 纤维的弯曲特性，类似于 RodZ 结合，并且表明这些突变体在单独缺乏 RodZ 或与野生型 MreB 结合的情况下挽救了杆状形状。因此，大肠杆菌可以通过差异调节 RodZ 和 MreB 来改变细胞壁插入的模式，从而控制其形状和尺寸，突出了细胞骨架分子生物物理学的丰富调节景观。
