Department of Molecular Genetics, 2 Department of Molecular and Cellular Biochemistry, and 3 Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210.
J Cell Biol. 2014 May 12;205(3):357-75. doi: 10.1083/jcb.201308146. Epub 2014 May 5.
The myosin-V family of molecular motors is known to be under sophisticated regulation, but our knowledge of the roles and regulation of myosin-Vs in cytokinesis is limited. Here, we report that the myosin-V Myo51 affects contractile ring assembly and stability during fission yeast cytokinesis, and is regulated by two novel coiled-coil proteins, Rng8 and Rng9. Both rng8Δ and rng9Δ cells display similar defects as myo51Δ in cytokinesis. Rng8 and Rng9 are required for Myo51's localizations to cytoplasmic puncta, actin cables, and the contractile ring. Myo51 puncta contain multiple Myo51 molecules and walk continuously on actin filaments in rng8(+) cells, whereas Myo51 forms speckles containing only one dimer and does not move efficiently on actin tracks in rng8Δ. Consistently, Myo51 transports artificial cargos efficiently in vivo, and this activity is regulated by Rng8. Purified Rng8 and Rng9 form stable higher-order complexes. Collectively, we propose that Rng8 and Rng9 form oligomers and cluster multiple Myo51 dimers to regulate Myo51 localization and functions.
肌球蛋白-V 家族的分子马达已被证实受到精细的调控，但我们对肌球蛋白-V 在胞质分裂中的作用和调控机制的了解还很有限。在这里，我们报告说肌球蛋白-V Myo51 影响有丝分裂酵母胞质分裂过程中环体的组装和稳定性，并受到两个新的卷曲螺旋蛋白 Rng8 和 Rng9 的调控。rng8Δ 和 rng9Δ 细胞在胞质分裂中表现出与 myo51Δ 相似的缺陷。Rng8 和 Rng9 对于 Myo51 定位于细胞质斑点、肌动蛋白纤维和收缩环是必需的。Myo51 斑点包含多个 Myo51 分子，并且在 rng8(+)细胞中在肌动蛋白丝上连续行走，而 Myo51 在 rng8Δ 中形成只包含一个二聚体的斑点，并且不能有效地在肌动蛋白轨道上移动。一致地，Myo51 在体内有效地运输人工货物，并且这种活性受到 Rng8 的调节。纯化的 Rng8 和 Rng9 形成稳定的高级复合物。总的来说，我们提出 Rng8 和 Rng9 形成寡聚体并聚集多个 Myo51 二聚体以调节 Myo51 的定位和功能。
