Trans-complex formation by proteolipid channels in the terminal phase of membrane fusion
Trans-complex formation by proteolipid channels in the terminal phase of membrane fusion
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DOI：
10.1038/35054500
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发表时间：
2001-02-01
期刊：
影响因子：
64.8
通讯作者：
Mayer, A
中科院分区：
文献类型：
--
作者：
Peters, C;Bayer, MJ;Mayer, A
SNARE（可溶性N-乙基马来酰亚胺敏感因子附着蛋白受体）和Rab-GTP酶及其辅因子介导囊泡膜融合中的附着步骤。但是双层混合--随后的融合核心过程--是如何被催化的仍然不清楚。Ca 2 +/钙调蛋白在许多细胞内融合事件中控制这一末端过程。在这里，我们确定V0，液泡H+-ATP酶的膜积分部门，作为酵母液泡钙调素的目标。在对接和双层融合之间，来自相对膜的V0扇区形成复合物。V0反式复合物的形成发生在反式SNARE配对的下游，并且依赖于Rab-GTdR Ypt 7和钙调蛋白。现有复合物的维持和融合的完成独立于反式SNARE对。重构的蛋白脂质形成密封通道，其可以以Ca 2 +/钙调蛋白依赖性方式扩张以形成水性孔。因此，V0反式复合物可以在融合位点形成连续的蛋白脂质内衬通道。我们认为这种蛋白质孔的径向扩张可能是细胞内膜融合的一种机制。
SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) and Rab-GTPases, together with their cofactors, mediate the attachment step in the membrane fusion of vesicles. But how bilayer mixing-the subsequent core process of fusion-is catalysed remains unclear. Ca2+/calmodulin controls this terminal process in many intracellular fusion events. Here we identify V0, the membrane-integral sector of the vacuolar H+-ATPase, as a target of calmodulin on yeast vacuoles. Between docking and bilayer fusion, V0 sectors from opposing membranes form complexes. V0 trans-complex formation occurs downstream from trans-SNARE pairing, and depends on both the Rab-GTPase Ypt7 and calmodulin. The maintenance of existing complexes and completion of fusion are independent of trans-SNARE pairs. Reconstituted proteolipids form sealed channels, which can expand to form aqueous pores in a Ca2+/calmodulin-dependent fashion. V0 trans-complexes may therefore form a continuous, proteolipid-lined channel at the fusion site. We propose that radial expansion of such a protein pore may be a mechanism for intracellular membrane fusion.