Mikrobiologie, Fakultät für Biologie, Universität Freiburg, 79104 Freiburg, Germany.
Mol Biol Cell. 2013 Aug;24(15):2340-9. doi: 10.1091/mbc.E12-10-0728. Epub 2013 Jun 19.
The maintenance of rod-cell shape in many bacteria depends on actin-like MreB proteins and several membrane proteins that interact with MreB. Using superresolution microscopy, we show that at 50-nm resolution, Bacillus subtilis MreB forms filamentous structures of length up to 3.4 μm underneath the cell membrane, which run at angles diverging up to 40° relative to the cell circumference. MreB from Escherichia coli forms at least 1.4-μm-long filaments. MreB filaments move along various tracks with a maximal speed of 85 nm/s, and the loss of ATPase activity leads to the formation of extended and static filaments. Suboptimal growth conditions lead to formation of patch-like structures rather than extended filaments. Coexpression of wild-type MreB with MreB mutated in the subunit interface leads to formation of shorter MreB filaments and a strong effect on cell shape, revealing a link between filament length and cell morphology. Thus MreB has an extended-filament architecture with the potential to position membrane proteins over long distances, whose localization in turn may affect the shape of the cell wall.
在许多细菌中，杆状细胞形状的维持依赖于肌动蛋白样 MreB 蛋白和几种与 MreB 相互作用的膜蛋白。使用超分辨率显微镜，我们发现，在 50nm 的分辨率下，枯草芽孢杆菌 MreB 在细胞膜下形成长达 3.4μm 的丝状结构，这些结构相对于细胞圆周以高达 40°的角度发散。大肠杆菌的 MreB 形成至少 1.4μm 长的丝。MreB 丝沿着各种轨迹以最大速度 85nm/s 移动，并且失去 ATP 酶活性会导致形成延伸和静态丝。在不合适的生长条件下，会形成点状结构而不是延伸的丝。野生型 MreB 与在亚基界面中突变的 MreB 共表达会导致形成更短的 MreB 丝，并对细胞形状产生强烈影响，这表明丝的长度与细胞形态之间存在联系。因此，MreB 具有延伸丝状结构，有可能将膜蛋白定位在长距离上，其定位反过来又可能影响细胞壁的形状。
