Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
J Cell Biol. 2010 Dec 27;191(7):1333-50. doi: 10.1083/jcb.201005134. Epub 2010 Dec 20.
Cytokinesis in animal and fungal cells utilizes a contractile actomyosin ring (AMR). However, how myosin II is targeted to the division site and promotes AMR assembly, and how the AMR coordinates with membrane trafficking during cytokinesis, remains poorly understood. Here we show that Myo1 is a two-headed myosin II in Saccharomyces cerevisiae, and that Myo1 localizes to the division site via two distinct targeting signals in its tail that act sequentially during the cell cycle. Before cytokinesis, Myo1 localization depends on the septin-binding protein Bni5. During cytokinesis, Myo1 localization depends on the IQGAP Iqg1. We also show that the Myo1 tail is sufficient for promoting the assembly of a "headless" AMR, which guides membrane deposition and extracellular matrix remodeling at the division site. Our study establishes a biphasic targeting mechanism for myosin II and highlights an underappreciated role of the AMR in cytokinesis beyond force generation.
动物和真菌细胞中的胞质分裂利用收缩的肌动球蛋白环（AMR）。然而，肌球蛋白 II 如何靶向分裂部位并促进 AMR 组装，以及 AMR 如何在胞质分裂过程中与膜运输协调，仍然知之甚少。在这里，我们表明 Myo1 是酿酒酵母中的一种双头肌球蛋白 II，Myo1 通过其尾部的两个不同靶向信号定位到分裂部位，这些信号在细胞周期中依次发挥作用。在胞质分裂之前，Myo1 的定位取决于 septin 结合蛋白 Bni5。在胞质分裂过程中，Myo1 的定位取决于 IQGAP Iqg1。我们还表明，Myo1 尾部足以促进“无头”AMR 的组装，该组装可指导分裂部位的膜沉积和细胞外基质重塑。我们的研究为肌球蛋白 II 的双相靶向机制奠定了基础，并强调了 AMR 在胞质分裂中除了产生力之外的作用。
