Molecular Cell Biology of Autophagy, The Francis Crick Institute, London NW1 1AT, UK.
Proteomics Science Technology Platform, The Francis Crick Institute, London NW1 1AT, UK.
Mol Cell. 2022 Nov 17;82(22):4324-4339.e8. doi: 10.1016/j.molcel.2022.10.017. Epub 2022 Nov 7.
ATG9A and ATG2A are essential core members of the autophagy machinery. ATG9A is a lipid scramblase that allows equilibration of lipids across a membrane bilayer, whereas ATG2A facilitates lipid flow between tethered membranes. Although both have been functionally linked during the formation of autophagosomes, the molecular details and consequences of their interaction remain unclear. By combining data from peptide arrays, crosslinking, and hydrogen-deuterium exchange mass spectrometry together with cryoelectron microscopy, we propose a molecular model of the ATG9A-2A complex. Using this integrative structure modeling approach, we identify several interfaces mediating ATG9A-2A interaction that would allow a direct transfer of lipids from ATG2A into the lipid-binding perpendicular branch of ATG9A. Mutational analyses combined with functional activity assays demonstrate their importance for autophagy, thereby shedding light on this protein complex at the heart of autophagy.
ATG9A 和 ATG2A 是自噬机制的核心必需组成部分。ATG9A 是一种脂质翻转酶，可使脂质在膜双层之间达到平衡，而 ATG2A 则促进连接膜之间的脂质流动。尽管在自噬体形成过程中它们的功能已被联系起来，但它们相互作用的分子细节和后果仍不清楚。通过将肽阵列、交联和氘氢交换质谱与冷冻电子显微镜相结合，我们提出了 ATG9A-2A 复合物的分子模型。使用这种综合结构建模方法，我们确定了介导 ATG9A-2A 相互作用的几个界面，这些界面允许将脂质从 ATG2A 直接转移到 ATG9A 的脂质结合垂直分支中。突变分析结合功能活性测定证明了它们对自噬的重要性，从而阐明了这个处于自噬核心的蛋白质复合物。
