Mikrobiologie, Fakultät für Biologie, Universität Freiburg, Freiburg, Germany.
PLoS One. 2011;6(11):e27035. doi: 10.1371/journal.pone.0027035. Epub 2011 Nov 1.
Actin-like bacterial cytoskeletal element MreB has been shown to be essential for the maintenance of rod cell shape in many bacteria. MreB forms rapidly remodelling helical filaments underneath the cell membrane in Bacillus subtilis and in other bacterial cells, and co-localizes with its two paralogs, Mbl and MreBH. We show that MreB localizes as dynamic bundles of filaments underneath the cell membrane in Drosophila S2 Schneider cells, which become highly stable when the ATPase motif in MreB is modified. In agreement with ATP-dependent filament formation, the depletion of ATP in the cells lead to rapid dissociation of MreB filaments. Extended induction of MreB resulted in the formation of membrane protrusions, showing that like actin, MreB can exert force against the cell membrane. Mbl also formed membrane associated filaments, while MreBH formed filaments within the cytosol. When co-expressed, MreB, Mbl and MreBH built up mixed filaments underneath the cell membrane. Membrane protein RodZ localized to endosomes in S2 cells, but localized to the cell membrane when co-expressed with Mbl, showing that bacterial MreB/Mbl structures can recruit a protein to the cell membrane. Thus, MreB paralogs form a self-organizing and dynamic filamentous scaffold underneath the membrane that is able to recruit other proteins to the cell surface.
肌动蛋白样细菌细胞骨架元件 MreB 已被证明对许多细菌中杆状细胞形状的维持是必不可少的。MreB 在枯草芽孢杆菌和其他细菌细胞的细胞膜下形成快速重塑的螺旋丝，并与它的两个平行物 Mbl 和 MreBH 共定位。我们表明，MreB 在果蝇 S2 Schneider 细胞的细胞膜下定位为动态纤维束，当 MreB 的 ATP 酶结构域发生修饰时，这些纤维束变得高度稳定。与 ATP 依赖性丝形成一致，细胞中 ATP 的耗尽导致 MreB 丝的快速解离。MreB 的延长诱导导致细胞膜突起的形成，表明与肌动蛋白一样，MreB 可以对细胞膜施加力。Mbl 也形成了与膜相关的纤维，而 MreBH 则在细胞质内形成纤维。当共表达时，MreB、Mbl 和 MreBH 在细胞膜下构建了混合纤维。膜蛋白 RodZ 在 S2 细胞中定位于内体，但与 Mbl 共表达时定位于细胞膜，表明细菌 MreB/Mbl 结构可以将一种蛋白质募集到细胞膜上。因此，MreB 平行物在膜下形成自我组织和动态的丝状支架，能够将其他蛋白质募集到细胞表面。
