The intracellular trafficking pathway, macroautophagy, is a recycling and disposal service that can be upregulated during periods of stress to maintain cellular homeostasis. An essential phase is the elongation and closure of the phagophore to seal and isolate unwanted cargo prior to lysosomal degradation. Human ATG2A and ATG2B proteins, through their interaction with WIPI proteins, are thought to be key players during phagophore elongation and closure, but little mechanistic detail is known about their function. We have identified a highly conserved motif driving the interaction between human ATG2 and GABARAP proteins that is in close proximity to the ATG2-WIPI4 interaction site. We show that the ATG2A-GABARAP interaction mutants are unable to form and close phagophores resulting in blocked autophagy, similar to ATG2A/ATG2B double-knockout cells. In contrast, the ATG2A-WIPI4 interaction mutant fully restored phagophore formation and autophagy flux, similar to wild-type ATG2A. Taken together, we provide new mechanistic insights into the requirements for ATG2 function at the phagophore and suggest that an ATG2-GABARAP/GABARAP-L1 interaction is essential for phagophore formation, whereas ATG2-WIPI4 interaction is dispensable.

中文翻译：

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保守的 ATG2-GABARAP 家族相互作用对于吞噬细胞的形成至关重要。

细胞内运输途径，即巨自噬，是一种回收和处置服务，可以在压力期间上调以维持细胞稳态。一个重要阶段是吞噬细胞的伸长和闭合，以在溶酶体降解之前密封和隔离不需要的货物。人类 ATG2A 和 ATG2B 蛋白通过它们与 WIPI 蛋白的相互作用，被认为是吞噬细胞伸长和闭合过程中的关键参与者，但对其功能的机制细节知之甚少。我们已经确定了一个高度保守的基序，它驱动人类 ATG2 和 GABARAP 蛋白之间的相互作用，该基序与 ATG2-WIPI4 相互作用位点非常接近。我们表明，ATG2A-GABARAP 相互作用突变体无法形成和关闭吞噬细胞，导致自噬受阻，类似于 ATG2A/ATG2B 双敲除细胞。相比之下，ATG2A-WIPI4 相互作用突变体完全恢复了吞噬细胞的形成和自噬通量，类似于野生型 ATG2A。总之，我们对吞噬细胞对 ATG2 功能的要求提供了新的机制见解，并建议 ATG2-GABARAP/GABARAP-L1 相互作用对于吞噬细胞的形成至关重要，而 ATG2-WIPI4 相互作用是可有可无的。