The yeast V159N actin mutant reveals roles for actin dynamics in vivo
The yeast V159N actin mutant reveals roles for actin dynamics in vivo
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DOI：
10.1083/jcb.142.5.1289
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发表时间：
1998-09-07
影响因子：
7.8
通讯作者：
Drubin, DG
中科院分区：
文献类型：
--
作者：
Belmont, LD;Drubin, DG
具有瓦尔159至Asn突变（V159 N）的肌动蛋白形成肌动蛋白丝，由于在无机磷酸盐释放后未能经历构象变化，所述肌动蛋白丝缓慢解聚。在这里，我们表明，这种肌动蛋白的表达结果在体内减少肌动蛋白动力学，我们利用这一属性来研究快速肌动蛋白丝周转的作用。表达V159 N突变体（act 1 -159）作为肌动蛋白唯一来源的酵母菌株比野生型酵母具有更大的皮质肌动蛋白斑块和更多的肌动蛋白电缆。快速的肌动蛋白动力学不是必需的皮层肌动蛋白补丁运动或建立细胞极性。然而，act 2 -159菌株的液相内吞作用是有缺陷的。Act 1 -159对于cofilin和profilin突变体是合成致死的，支持所有这些基因中的突变损害聚合/解聚循环的结论。与此相反，act 1 -159部分抑制温度敏感性的原肌球蛋白突变体，和细胞质电缆中看到的fimplant，Mdm 20 p和原肌球蛋白无效突变体的损失，这表明这些肌动蛋白结合蛋白的丝稳定功能。在这些双突变体细胞中的电缆的分析支持fimalphine在组织细胞质电缆和Mdm 20 p和原肌球蛋白在排除cofilin从电缆的作用。
Actin with a Val 159 to Asn mutation (V159N) forms actin filaments that depolymerize slowly because of a failure to undergo a conformational change after inorganic phosphate release. Here we demonstrate that expression of this actin results in reduced actin dynamics in vivo, and we make use of this property to study the roles of rapid actin filament turnover. Yeast strains expressing the V159N mutant (act1-159) as their only source of actin have larger cortical actin patches and more actin cables than wild-type yeast. Rapid actin dynamics are not essential for cortical actin patch motility or establishment of cell polarity. However, fluid phase endocytosis is defective in act2-159 strains. act1-159 is synthetically lethal with cofilin and profilin mutants, supporting the conclusion that mutations in all of these genes impair the polymerization/depolymerization cycle. In contrast, act1-159 partially suppresses the temperature sensitivity of a tropomyosin mutant, and the loss of cytoplasmic cables seen in fimbrin, Mdm20p, and tropomyosin null mutants, suggesting filament stabilizing functions for these actin-binding proteins. Analysis of the cables in these double-mutant cells supports a role for fimbrin in organizing cytoplasmic cables and for Mdm20p and tropomyosin in excluding cofilin from the cables.