Membrane tethering by the atlastin GTPase depends on GTP hydrolysis but not on forming the cross-over configuration.
Membrane tethering by the atlastin GTPase depends on GTP hydrolysis but not on forming the cross-over configuration.
复制标题
阿特拉斯丁 GTP 酶的膜拴系作用取决于 GTP 的水解，但不取决于交叉构型的形成。
DOI：
10.1091/mbc.e14-08-1284
复制
发表时间：
2014-12-01
影响因子：
3.3
通讯作者：
Lee TH
中科院分区：
文献类型：
--
作者：
Saini SG;Liu C;Zhang P;Lee TH
atlastin GT3将核苷酸水解偶联形成反式交叉二聚体以催化同型内质网膜融合。分离栓系与融合的测定揭示了栓系的稳定反式接触依赖于GTP水解。相比之下，仅在融合步骤中需要交叉形成。膜锚定的atlastin GTdR将核苷酸水解偶联到同型膜融合的催化，以形成分支的内质网网络。锚定在相对膜中的atlastins之间的反式二聚化，伴随着交叉构象变化，被认为将膜吸引在一起以进行融合。以前的研究已经进行了很大程度上的atlastins缺乏一个膜锚的构象偶联atlastin的GTP水解循环。因此，融合是否涉及离散的拴系步骤，如果是这样，GTP水解和交换在拴系中的潜在作用仍然未知。在这项研究中，我们使用膜锚定的atlastins的测定，分离拴从融合解剖的要求。我们发现，拴系依赖于GTP水解，但与融合不同，它不依赖于交叉。因此，GTP水解引发稳定的头域接触，反式拴系相对的膜，而交叉形成中起着更关键的作用，在供电的脂质重排融合。
The atlastin GTPase couples nucleotide hydrolysis to formation of a trans cross-over dimer to catalyze homotypic endoplasmic reticulum membrane fusion. Assays that separate tethering from fusion reveal that stable trans contact for tethering depends on GTP hydrolysis. In contrast, cross-over formation is required only for the fusion step. The membrane-anchored atlastin GTPase couples nucleotide hydrolysis to the catalysis of homotypic membrane fusion to form a branched endoplasmic reticulum network. Trans dimerization between atlastins anchored in opposing membranes, accompanied by a cross-over conformational change, is thought to draw the membranes together for fusion. Previous studies on the conformational coupling of atlastin to its GTP hydrolysis cycle have been carried out largely on atlastins lacking a membrane anchor. Consequently, whether fusion involves a discrete tethering step and, if so, the potential role of GTP hydrolysis and cross-over in tethering remain unknown. In this study, we used membrane-anchored atlastins in assays that separate tethering from fusion to dissect the requirements for each. We found that tethering depended on GTP hydrolysis, but, unlike fusion, it did not depend on cross-over. Thus GTP hydrolysis initiates stable head-domain contact in trans to tether opposing membranes, whereas cross-over formation plays a more pivotal role in powering the lipid rearrangements for fusion.