Axonemal dynein light chain-1 locates at the microtubule-binding domain of the γ heavy chain.
Axonemal dynein light chain-1 locates at the microtubule-binding domain of the γ heavy chain.
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DOI：
10.1091/mbc.e15-05-0289
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发表时间：
2015-11-15
影响因子：
3.3
通讯作者：
Toyoshima YY
中科院分区：
文献类型：
--
作者：
Ichikawa M;Saito K;Yanagisawa HA;Yagi T;Kamiya R;Yamaguchi S;Yajima J;Kushida Y;Nakano K;Numata O;Toyoshima YY
外臂动力蛋白（OAD）复合物的动力蛋白轻链1（LC 1）与复合物内γ重链的微管结合域（MTBD）结合。LC 1被认为通过调节γ MTBD对轴丝中的双微管的B-小管的亲和力来调节OAD活性和纤毛/鞭毛运动。外臂动力蛋白（OAD）复合物是纤毛/鞭毛搏动的主要推进力发生器。在衣原体和四膜虫中，OAD复合体包含三条重链（α、β和γ HC）和>10个较小的亚基。动力蛋白轻链-1（LC 1）是OAD的重要组成部分。已知其与衣原体γ头部结构域相关，但其在γ头部内的精确定位和OAD复合物的调节机制仍不清楚。在此，Ni-NTA-纳米金标记电子显微镜将LC 1定位于γ头部的柄端。单粒子分析检测到一个额外的结构，最有可能对应于LC 1，附近的微管结合域（MTBD），位于茎尖。拉下试验证实LC 1特异性结合γ MTBD区域。结合LC 1降低γ MTBD对微管亲和力的观察结果，我们提出了一个新的模型，其中LC 1通过调节γ MTBD对双微管的亲和力来调节OAD活性。
Dynein light chain 1 (LC1) of the outer arm dynein (OAD) complex associates with the microtubule-binding domain (MTBD) of γ heavy chain inside the complex. LC1 is considered to regulate the OAD activity and ciliary/flagellar motion by modulating γ MTBD's affinity to the B-tubule of the doublet microtubule in the axoneme. The outer arm dynein (OAD) complex is the main propulsive force generator for ciliary/flagellar beating. In Chlamydomonas and Tetrahymena, the OAD complex comprises three heavy chains (α, β, and γ HCs) and >10 smaller subunits. Dynein light chain-1 (LC1) is an essential component of OAD. It is known to associate with the Chlamydomonas γ head domain, but its precise localization within the γ head and regulatory mechanism of the OAD complex remain unclear. Here Ni-NTA-nanogold labeling electron microscopy localized LC1 to the stalk tip of the γ head. Single-particle analysis detected an additional structure, most likely corresponding to LC1, near the microtubule-binding domain (MTBD), located at the stalk tip. Pull-down assays confirmed that LC1 bound specifically to the γ MTBD region. Together with observations that LC1 decreased the affinity of the γ MTBD for microtubules, we present a new model in which LC1 regulates OAD activity by modulating γ MTBD's affinity for the doublet microtubule.