Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
J Cell Biol. 2013 Feb 4;200(3):271-86. doi: 10.1083/jcb.201208030. Epub 2013 Jan 28.
Core components of cytokinesis are conserved from yeast to human, but how these components are assembled into a robust machine that drives cytokinesis remains poorly understood. In this paper, we show by fluorescence recovery after photobleaching analysis that Myo1, the sole myosin-II in budding yeast, was mobile at the division site before anaphase and became immobilized shortly before cytokinesis. This immobility was independent of actin filaments or the motor domain of Myo1 but required a small region in the Myo1 tail that is thought to be involved in higher-order assembly. As expected, proteins involved in actin ring assembly (tropomyosin and formin) and membrane trafficking (myosin-V and exocyst) were dynamic during cytokinesis. Strikingly, proteins involved in septum formation (the chitin synthase Chs2) and/or its coordination with the actomyosin ring (essential light chain, IQGAP, F-BAR, etc.) displayed Myo1-dependent immobility during cytokinesis, suggesting that Myo1 plays a scaffolding role in the assembly of a cytokinesis machine.
细胞分裂的核心组件在从酵母到人之间是保守的，但这些组件如何组装成一个强大的机器来驱动细胞分裂，仍然知之甚少。在本文中，我们通过光漂白后荧光恢复分析表明，在有丝分裂后期之前，出芽酵母中唯一的肌球蛋白 II Myo1 在分裂位点是可动的，并且在细胞分裂前不久就固定不动了。这种不活动不依赖于肌动蛋白丝或 Myo1 的运动结构域，但需要 Myo1 尾部的一个小区域，该区域被认为参与高级组装。正如预期的那样，参与肌动球蛋白环组装（原肌球蛋白和形成素）和膜运输（肌球蛋白-V 和外泌体）的蛋白质在细胞分裂过程中是动态的。引人注目的是，参与隔膜形成（几丁质合成酶 Chs2）及其与肌动球蛋白环协调的蛋白质（必需轻链、IQGAP、F-BAR 等）在细胞分裂过程中表现出 Myo1 依赖性的不活动，表明 Myo1 在细胞分裂机器的组装中发挥支架作用。
