Department of Biology, Texas A&M University, College Station, TX 77843.
Department of Physics, University of California, Berkeley, CA 94720.
Proc Natl Acad Sci U S A. 2018 Mar 6;115(10):2484-2489. doi: 10.1073/pnas.1716441115. Epub 2018 Feb 20.
MreB is a bacterial actin that is important for cell shape and cell wall biosynthesis in many bacterial species. MreB also plays crucial roles in gliding motility, but the underlying mechanism remains unknown. Here we tracked the dynamics of single MreB particles in using single-particle tracking photoactivated localization microscopy. We found that a subpopulation of MreB particles moves rapidly along helical trajectories, similar to the movements of the MotAB-like gliding motors. The rapid MreB motion was stalled in the mutants that carried truncated gliding motors. Remarkably, MreB moves one to two orders of magnitude faster than its homologs that move along with the cell wall synthesis machinery in and , and this rapid movement was not affected by the inhibitors of cell wall biosynthesis. Our results show that in , MreB provides a scaffold for the gliding motors while the gliding machinery drives the movement of MreB filaments, analogous to the interdependent movements of myosin motors and actin in eukaryotic cells.
MreB 是一种细菌肌动蛋白,对于许多细菌物种的细胞形状和细胞壁生物合成都很重要。MreB 还在滑动运动中发挥着至关重要的作用,但潜在的机制尚不清楚。在这里,我们使用单粒子追踪光激活定位显微镜追踪了单个 MreB 颗粒在 中的动力学。我们发现,一部分 MreB 颗粒沿螺旋轨迹快速移动,类似于 MotAB 样滑动马达的运动。在携带截短滑动马达的突变体中,快速的 MreB 运动被阻止。值得注意的是,MreB 的移动速度比其在 和 中与细胞壁合成机制一起移动的同源物快一到两个数量级,而且这种快速运动不受细胞壁生物合成抑制剂的影响。我们的结果表明,在 中,MreB 为滑动马达提供了一个支架,而滑动机制则驱动 MreB 丝的运动,类似于真核细胞中肌球蛋白马达和肌动蛋白的相互依赖运动。