Electron cryotomography of ESCRT assemblies and dividing Sulfolobus cells suggests that spiraling filaments are involved in membrane scission.
Electron cryotomography of ESCRT assemblies and dividing Sulfolobus cells suggests that spiraling filaments are involved in membrane scission.
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DOI：
10.1091/mbc.e12-11-0785
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发表时间：
2013-08
影响因子：
3.3
通讯作者：
Jensen GJ
中科院分区：
文献类型：
--
作者：
Dobro MJ;Samson RY;Yu Z;McCullough J;Ding HJ;Chong PL;Bell SD;Jensen GJ
ESCRT细丝螺旋缠绕在脂质体周围，并在体外组装成各种螺旋结构。分裂Sulfolobus细胞进一步表现出薄的、动态的带涂层分裂沟。这些数据共同表明，螺旋丝参与膜断裂。运输所需的内体分选复合物（ESCRT）在进化上是保守的，从古生物到真核生物。该复合体在一系列过程中驱动膜断裂事件，包括后生动物和一些寄生虫中的胞质分裂。CdvA是一种蛋白质，它将ESCRT-III募集到细胞膜上。使用电子冷冻断层扫描（ECT），我们发现，CdvA聚合成螺旋细丝包裹在脂质体。ESCRT-III蛋白负责膜的收紧，并已被证明在体外组装成螺旋管，但在这里，我们表明，它们也可以形成嵌套管和嵌套锥，这揭示了令人惊讶的众多和通用的接触。为了观察ESCRT-CdvA复合物在生理背景下，我们使用ECT的古菌硫化叶菌acidocaldarius的图像，并观察到一个独特的蛋白质带收缩沟在分裂细胞的前缘。ESCRT-III蛋白的已知尺寸限制了它们在这些结构中的每一个内的可能取向，并指出螺旋丝参与膜断裂。
ESCRT filaments wrap helically around liposomes and assemble into various helical structures in vitro. Dividing Sulfolobus cells further exhibit a thin, dynamic belt coating division furrows. Together these data suggest that spiraling filaments are involved in membrane scission. The endosomal-sorting complex required for transport (ESCRT) is evolutionarily conserved from Archaea to eukaryotes. The complex drives membrane scission events in a range of processes, including cytokinesis in Metazoa and some Archaea. CdvA is the protein in Archaea that recruits ESCRT-III to the membrane. Using electron cryotomography (ECT), we find that CdvA polymerizes into helical filaments wrapped around liposomes. ESCRT-III proteins are responsible for the cinching of membranes and have been shown to assemble into helical tubes in vitro, but here we show that they also can form nested tubes and nested cones, which reveal surprisingly numerous and versatile contacts. To observe the ESCRT–CdvA complex in a physiological context, we used ECT to image the archaeon Sulfolobus acidocaldarius and observed a distinct protein belt at the leading edge of constriction furrows in dividing cells. The known dimensions of ESCRT-III proteins constrain their possible orientations within each of these structures and point to the involvement of spiraling filaments in membrane scission.