Ugo1 and Mdm30 act sequentially during Fzo1-mediated mitochondrial outer membrane fusion
Ugo1 and Mdm30 act sequentially during Fzo1-mediated mitochondrial outer membrane fusion
复制标题
DOI：
10.1242/jcs.073080
复制
发表时间：
2011-04-01
影响因子：
4
通讯作者：
Escobar-Henriques, Mafalda
中科院分区：
文献类型：
--
作者：
Anton, Fabian;Fres, Julia M.;Escobar-Henriques, Mafalda
动力蛋白相关GTPase蛋白（DRPs）是膜重构的主要参与者。保守的DRPs称为丝裂蛋白（Mfn1/Mfn2/Fzo1）介导线粒体外膜（OM）的融合。OM融合依赖于有丝分裂蛋白的自组装和GTPase活性，以及另外两种蛋白，Ugo1和Mdm30。在这里，我们使用体外和体内方法定义了OM融合周期的不同步骤。我们证明酵母Fzo1组装成同型二聚体，依赖于Ugo1和GTP与Fzo1的结合。Fzo1同型二聚体在形成线粒体接触时进一步结合，允许膜系住。随后的GTP水解是Fzo1被F-box蛋白Mdm30泛素化所必需的。最后，依赖mdm30的Fzo1降解完成了Fzo1在OM融合中的功能。因此，我们的研究结果揭示了Ugo1和Mdm30在OM融合过程中不同步骤的功能，并表明蛋白质清除赋予有丝分裂蛋白一种非循环机制，这与其他细胞膜融合事件不同。
Dynamin-related GTPase proteins (DRPs) are main players in membrane remodelling. Conserved DRPs called mitofusins (Mfn1/Mfn2/Fzo1) mediate the fusion of mitochondrial outer membranes (OM). OM fusion depends on self-assembly and GTPase activity of mitofusins as well as on two other proteins, Ugo1 and Mdm30. Here, we define distinct steps of the OM fusion cycle using in vitro and in vivo approaches. We demonstrate that yeast Fzo1 assembles into homo-dimers, depending on Ugo1 and on GTP binding to Fzo1. Fzo1 homo-dimers further associate upon formation of mitochondrial contacts, allowing membrane tethering. Subsequent GTP hydrolysis is required for Fzo1 ubiquitylation by the F-box protein Mdm30. Finally, Mdm30-dependent degradation of Fzo1 completes Fzo1 function in OM fusion. Our results thus unravel functions of Ugo1 and Mdm30 at distinct steps during OM fusion and suggest that protein clearance confers a non-cycling mechanism to mitofusins, which is distinct from other cellular membrane fusion events.