Essential functions and actin-binding surfaces of yeast cofilin revealed by systematic mutagenesis
Essential functions and actin-binding surfaces of yeast cofilin revealed by systematic mutagenesis
复制标题
DOI：
10.1093/emboj/16.18.5520
复制
发表时间：
1997-09-15
期刊：
影响因子：
11.4
通讯作者：
Drubin, DG
中科院分区：
文献类型：
--
作者：
Lappalainen, P;Fedorov, EV;Drubin, DG
Cofilin在体内刺激肌动蛋白丝更新。对20株酵母cofilin突变体进行了表型测定，其中10株生长良好，无细胞骨架缺陷，7株隐性致死，3株条件致死，并引起严重的肌动蛋白结构缺陷。对9株酵母cofilin突变体与肌动蛋白相互作用的生化特性进行了研究，证明F-肌动蛋白结合和解聚是cofilin的基本功能，通过对酵母cofilin分子结构中突变残基的定位，得出了几个重要的结论：第一，肌动蛋白单体结合所需的残基彼此相邻，第二，与肌动蛋白丝相互作用需要额外的残基;这些残基可能与肌动蛋白丝中的相邻亚基结合。第三，尽管结构惊人相似，丝切蛋白与肌动蛋白的相互作用方式与凝溶胶蛋白片段-1不同。第四，通过鉴定对体内丝切蛋白功能重要的空间近端残基，但对体外肌动蛋白相互作用不重要，表明以前未认识到的丝切蛋白功能或相互作用，最后，cofilin N-末端的突变表明其序列是保守的，因为它在肌动蛋白相互作用中起关键作用，而不是因为它有时是蛋白激酶的靶标。
Cofilin stimulates actin filament turnover in vivo. The phenotypes of twenty yeast cofilin mutants generated by systematic mutagenesis were determined, Ten grew as well as the wild type and showed no cytoskeleton defects, seven were recessive-lethal and three were conditional-lethal and caused severe actin organization defects, Biochemical characterization of interactions between nine mutant yeast cofilins and yeast actin provided evidence that F-actin binding and depolymerization are essential cofilin functions, Locating the mutated residues on the yeast cofilin molecular structure allowed several important conclusions to be drawn, First, residues required for actin monomer binding are proximal to each other, Secondly, additional residues are required for interactions with actin filaments; these residues might bind an adjacent subunit in the actin filament, Thirdly, despite striking structural similarity, cofilin interacts with actin in a different manner from gelsolin segment-1, Fourthly, a previously unrecognized cofilin function or interaction is suggested by identification of spatially proximal residues important for cofilin function in vivo, but not for actin interactions in vitro, Finally, mutation of the cofilin N-terminus suggests that its sequence is conserved because of its critical role in actin interactions, not because it is sometimes a target for protein kinases.