Molecular Mechanism of Autophagic Membrane-Scaffold Assembly and Disassembly
Molecular Mechanism of Autophagic Membrane-Scaffold Assembly and Disassembly
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DOI：
10.1016/j.cell.2013.12.022
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发表时间：
2014-01-30
期刊：
影响因子：
64.5
通讯作者：
Wollert, Thomas
中科院分区：
文献类型：
--
作者：
Kaufmann, Anna;Beier, Viola;Wollert, Thomas
自噬是一种分解代谢途径，其将不需要的细胞物质隔离到自噬体中以递送到溶酶体进行降解。该途径中的关键步骤是泛素相关蛋白Atg 8与自噬膜中的磷脂酰乙醇胺（Atg 8-PE）通过由Atg 16和Atg 12 Atg 5缀合物组成的复合物共价缀合。atg 8控制自噬前体膜的扩张，但其潜在机制尚不清楚。在这里，我们重建Atg 8共轭巨单层囊泡和支持脂质双层。我们发现Atg 8-PE与Atg 12-Atg 5-Atg 16缔合成膜支架。相比之下，支架形成被线粒体货物衔接子Atg 32通过与Atg 12-Atg 5竞争Atg 8结合而抵消。Atg 4，以前已知从膜回收Atg 8，分解支架。重要的是，Atg 12和Atg 16的突变体在体外支架形成中的缺陷会损害体内的自噬。这表明自噬支架对于吞噬细胞生物发生和自噬是至关重要的。
Autophagy is a catabolic pathway that sequesters undesired cellular material into autophagosomes for delivery to lysosomes for degradation. A key step in the pathway is the covalent conjugation of the ubiquitin-related protein Atg8 to phosphatidylethanolamine (Atg8-PE) in autophagic membranes by a complex consisting of Atg16 and the Atg12Atg5 conjugate. Atg8 controls the expansion of autophagic precursor membranes, but the underlying mechanism remains unclear. Here, we reconstitute Atg8 conjugation on giant unilamellar vesicles and supported lipid bilayers. We found that Atg8-PE associates with Atg12-Atg5-Atg16 into a membrane scaffold. By contrast, scaffold formation is counteracted by the mitochondrial cargo adaptor Atg32 through competition with Atg12-Atg5 for Atg8 binding. Atg4, previously known to recycle Atg8 from membranes, disassembles the scaffold. Importantly, mutants of Atg12 and Atg16 deficient in scaffold formation in vitro impair autophagy in vivo. This suggests that autophagic scaffolds are critical for phagophore biogenesis and thus autophagy.