近日，美国宾州大学Roberto Dominguez及其小组揭示肌动蛋白丝自由端和加帽端的结构。该项研究成果于2023年5月25日在线发表在《科学》杂志上。

研究人员描述了F-肌动蛋白的自由端和加帽端的冷冻电镜结构。自由刺端的终端亚单位采用“平坦”的F-肌动蛋白构象。CapZ与刺端结合时，与刺端发生微小的变化，但与自身发生重大变化。相反，位于自由尖端的亚单位采用“扭曲的”G-肌动蛋白构象。原肌球蛋白调节蛋白的结合迫使第二个亚单位进入F-actin构象。这些结构揭示了F-肌动蛋白的两端与中间有什么不同，以及这些不同如何控制亚单位的添加/分离、加帽以及与末端结合蛋白的相互作用。

据介绍，肌动蛋白丝（F-肌动蛋白）的刺端和尖端是生长/收缩的部位，也是阻断亚单位交换的加帽蛋白的靶标，包括位于刺端的CapZ和位于尖端的原肌球蛋白调节蛋白。

附：英文原文

Title: Structures of the free and capped ends of the actin filament

Author: Peter J. Carman, Kyle R. Barrie, Grzegorz Rebowski, Roberto Dominguez

Issue&Volume: 2023-05-25

Abstract: The barbed and pointed ends of the actin filament (F-actin) are the sites of growth/shrinkage and the targets of capping proteins that block subunit exchange, including CapZ at the barbed end and tropomodulin at the pointed end. We describe cryo-electron microscopy structures of the free and capped ends of F-actin. Terminal subunits at the free barbed end adopt a “flat” F-actin conformation. CapZ binds with minor changes to the barbed end but major changes to itself. In contrast, subunits at the free pointed end adopt a “twisted” G-actin conformation. Tropomodulin binding forces the second subunit into an F-actin conformation. The structures reveal how the ends differ from the middle in F-actin and how these differences control subunit addition/dissociation, capping, and interactions with end-binding proteins.

DOI: adg6812

Source: https://www.science.org/doi/10.1126/science.adg6812