Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08540, USA.
Proc Natl Acad Sci U S A. 2011 May 3;108(18):7559-64. doi: 10.1073/pnas.1101101108. Epub 2011 Apr 11.
Protein-directed intracellular transport has not been observed in bacteria despite the existence of dynamic protein localization and a complex cytoskeleton. However, protein trafficking has clear potential uses for important cellular processes such as growth, development, chromosome segregation, and motility. Conflicting models have been proposed to explain Myxococcus xanthus motility on solid surfaces, some favoring secretion engines at the rear of cells and others evoking an unknown class of molecular motors distributed along the cell body. Through a combination of fluorescence imaging, force microscopy, and genetic manipulation, we show that membrane-bound cytoplasmic complexes consisting of motor and regulatory proteins are directionally transported down the axis of a cell at constant velocity. This intracellular motion is transmitted to the exterior of the cell and converted to traction forces on the substrate. Thus, this study demonstrates the existence of a conserved class of processive intracellular motors in bacteria and shows how these motors have been adapted to produce cell motility.
尽管存在动态的蛋白质定位和复杂的细胞骨架，但在细菌中尚未观察到蛋白导向的细胞内运输。然而，蛋白运输对于重要的细胞过程（如生长、发育、染色体分离和运动）具有明显的潜在用途。已经提出了相互矛盾的模型来解释粘细菌在固体表面上的运动，一些模型支持细胞后部的分泌引擎，而另一些则唤起了沿细胞体分布的未知类别的分子马达。通过荧光成像、力显微镜和遗传操作的结合，我们表明由马达和调节蛋白组成的膜结合细胞质复合物以恒定速度沿细胞轴定向运输。这种细胞内运动被传递到细胞外部，并转化为对基质的牵引力。因此，本研究证明了在细菌中存在一类保守的连续的细胞内马达，并展示了这些马达如何被适应以产生细胞运动。
