The actin cytoskeleton plays a variety of roles in eukaryotic cell physiology, ranging from cell polarity and migration to cytokinesis. Key to the function of the actin cytoskeleton is the mechanisms that control its assembly, stability, and turnover. Through genetic analyses in S. pombe, we found that, myo2-S1 (myo2-G515D), a myosin II mutant allele, was capable of rescuing lethality caused by partial defects in actin nucleation / stability caused, for example, through compromised function of the actin-binding protein Cdc3-profilin. The mutation in myo2-S1 affects the activation loop of Myosin II, which is involved in physical interaction with subdomain 1 of actin and in stimulating the ATPase activity of Myosin. Consistently, actomyosin rings in myo2-S1 cell ghosts were unstable and severely compromised in contraction upon ATP addition. These studies strongly suggest a role for Myo2 in actin cytoskeletal disassembly and turnover in vivo, and that compromise of this activity leads to genetic suppression of mutants defective in actin filament assembly / stability at the division site.

肌动蛋白的细胞骨架在真核细胞生理学中起多种作用，范围从细胞极性和迁移到胞质分裂。肌动蛋白细胞骨架功能的关键是控制其组装，稳定性和周转的机制。通过对粟酒裂殖酵母的遗传分析，我们发现，肌球蛋白II突变体等位基因myo2 -S1（myo2 -G515D）能够挽救因肌动蛋白成核/稳定性的部分缺陷（例如，通过破坏蛋白的功能而引起）所致的杀伤力。肌动蛋白结合蛋白Cdc3-profilin。myo2中的突变-S1影响肌球蛋白II的激活环，后者与肌动蛋白的亚结构域1发生物理相互作用并刺激肌球蛋白的ATPase活性。一致地，肌球蛋白S环在myo2 -S1细胞幽灵中不稳定，并且在添加ATP后收缩中受到严重损害。这些研究强烈暗示了Myo2在体内肌动蛋白细胞骨架的分解和更新中的作用，并且这种活性的损害导致遗传抑制肌动蛋白丝组装/分裂位点稳定性的突变体。