Molecular dissection of the actin-binding ability of the fission yeast α-actinin, Ain1, in vitro and in vivo
Molecular dissection of the actin-binding ability of the fission yeast α-actinin, Ain1, in vitro and in vivo
复制标题
裂殖酵母 α-肌动蛋白 Ain1 肌动蛋白结合能力的体外和体内分子解析
DOI：
10.1093/jb/mvx008
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Nakano Kentaro
中科院分区：
文献类型：
--
作者：
Morita Rikuri;Takaine Masak;Numata Osamu;Nakano Kentaro
收缩环（CR）参与动物和酵母细胞的胞质分裂。虽然有几种类型的肌动蛋白捆绑蛋白与F-肌动蛋白在CR，他们的个人角色在CR尚未得到详细阐明。Ain 1是裂殖酵母裂殖酵母中唯一的α-辅肌动蛋白同源物，特异性定位于CR，具有高转换率。缺乏theain 1+基因的粟粒细胞在应激条件下表现出胞质分裂缺陷。本文研究了Ain 1的生物化学活性和细胞定位机制。在粟酒裂殖酵母中，Ain 1与F-辅肌动蛋白的亲和力比其他辅肌动蛋白捆绑蛋白弱。我们确定了一个突变，大概松动的两个calponin同源结构域之间的相互作用构成的单一肌动蛋白结合域（ABD）的Ain 1，这加强了肌动蛋白结合活性的Ain 1。该突变蛋白诱导CR的环形变形。无论是一个截短的蛋白质组成的N-末端ABD，也没有一个截短的蛋白质缺乏一个C-末端区域含有EF-手基序本地化的CR，而后者参与捆绑的F-辅肌动蛋白体外。我们在此提出了详细的机制，分子的每个部分是如何参与适当的细胞定位和功能的Ain 1。
A contractile ring (CR) is involved in cytokinesis in animal and yeast cells. Although several types of actin-bundling proteins associate with F-actin in the CR, their individual roles in the CR have not yet been elucidated in detail. Ain1 is the sole α-actinin homologue in the fission yeastSchizosaccharomyces pombeand specifically localizes to the CR with a high turnover rate.S. pombecells lacking theain1+gene show defects in cytokinesis under stress conditions. We herein investigated the biochemical activity and cellular localization mechanisms of Ain1. Ain1 showed weaker affinity to F-actinin vitrothan other actin-bundling proteins inS. pombe. We identified a mutation that presumably loosened the interaction between two calponin-homology domains constituting the single actin-binding domain (ABD) of Ain1, which strengthened the actin-binding activity of Ain1. This mutant protein induced a deformation in the ring shape of the CR. Neither a truncated protein consisting only of an N-terminal ABD nor a truncated protein lacking a C-terminal region containing an EF-hand motif localized to the CR, whereas the latter was involved in the bundling of F-actinin vitro. We herein propose detailed mechanisms for how each part of the molecule is involved in the proper cellular localization and function of Ain1.