THRUMIN1 Is a Light-Regulated Actin-Bundling Protein Involved in Chloroplast Motility
THRUMIN1 Is a Light-Regulated Actin-Bundling Protein Involved in Chloroplast Motility
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DOI：
10.1016/j.cub.2010.11.059
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发表时间：
2011-01-11
期刊：
影响因子：
9.2
通讯作者：
Hangarter, Roger P.
中科院分区：
文献类型：
--
作者：
Whippo, Craig W.;Khurana, Parul;Hangarter, Roger P.
叶绿体运动响应光条件的变化，优化光合光吸收[1]。这种重新定位由蓝光刺激，蓝光通过向光蛋白光感受器感知[2-4]，并被转导到肌动蛋白细胞骨架[5]。一些基于肌动蛋白的运动系统使用细丝重组而不是基于肌球蛋白的易位[6]。最近的研究支持叶绿体运动是由质膜上的肌动蛋白重组驱动的假设[7，8]，但没有影响叶绿体运动的蛋白质被证明与体内质膜和肌动蛋白丝相关。在这里，我们确定了促凝血酶1，在质膜上的光致激素感光活性和肌动蛋白依赖的叶绿体运动之间的关键环节。THRUMIN 1在体外将丝状肌动蛋白束成束，并且其定位于质膜，并且在体内显示光和向光蛋白依赖性定位于微丝。这些结果表明，光诱导肌动蛋白捆绑通过THRUMIN 1是重要的叶绿体运动。促甲状腺激素1的哺乳动物同源物GRXCR 1作为肌动蛋白结构的调节剂与听觉反应和毛细胞静纤毛发育有关[9，10]。对促凝血酶1的研究将有助于阐明这一真核蛋白家族的功能。
Chloroplast movement in response to changing light conditions optimizes photosynthetic light absorption [1]. This repositioning is stimulated by blue light perceived via the phototropin photoreceptors [2-4] and is transduced to the actin cytoskeleton [5]. Some actin-based motility systems use filament reorganizations rather than myosin-based translocations [6]. Recent research favors the hypothesis that chloroplast movement is driven by actin reorganization at the plasma membrane [7, 8], but no proteins affecting chloroplast movements have been shown to associate with both the plasma membrane and actin filaments in vivo. Here we identified THRUMIN1 as, a critical link between phototropin photoreceptor activity at the plasma membrane and actin-dependent chloroplast movements. THRUMIN1 bundles filamentous actin in vitro, and it localizes to the plasma membrane and displays light- and phototropin-dependent localization to microfilaments in vivo. These results suggest that phototropin-induced actin bundling via THRUMIN1 is important for chloroplast movement. A mammalian homolog of THRUMIN1, GRXCR1, has been implicated in auditory responses and hair cell stereocilia development as a regulator of actin architecture [9, 10]. Studies of THRUMIN1 will help elucidate the function of this family of eukaryotic proteins.