Selective autophagy is the capture of specific cytosolic contents in double-membrane vesicles that subsequently fuse with the vacuole or lysosome, thereby delivering cargo for degradation. Selective autophagy receptors (SARs) mark the cargo for degradation and, in yeast, recruit Atg11, the scaffolding protein for selective autophagy initiation. The mitochondrial protein Atg32 is the yeast SAR that mediates mitophagy, the selective autophagic capture of mitochondria. Atg11–Atg32 interactions concentrate Atg32 into puncta that are thought to represent sites of mitophagy initiation. However, it is unclear how Atg11 concentrates Atg32 to generate mitophagy initiation sites. We show here that the coiled coil 3 (CC3) domain of Atg11 is required for concentrating Atg32 into puncta. We determined the structure of the majority of the CC3, demonstrating that the CC3 forms a parallel homodimer whose dimer interface is formed by a small number of hydrophobic residues. We further show that the CC3 interface is not required for Atg11 dimerization but is required for shaping Atg32 into functional mitophagy initiation sites and for delivery of mitochondria to the vacuole. Our findings suggest that Atg11 self-interactions help concentrate SARs as a necessary precondition for cargo capture.

选择性自噬是在双膜囊泡中捕获特定的细胞质内容物，随后与液泡或溶酶体融合，从而提供降解的货物。选择性自噬受体 (SAR) 标记要降解的货物，并在酵母中募集 Atg11，这是选择性自噬起始的支架蛋白。线粒体蛋白 Atg32 是介导线粒体自噬的酵母 SAR，线粒体的选择性自噬捕获。Atg11-Atg32 相互作用将 Atg32 浓缩到被认为代表线粒体自噬起始位点的斑点中。然而，尚不清楚 Atg11 如何浓缩 Atg32 以产生线粒体自噬起始位点。我们在这里展示了 Atg11 的卷曲线圈 3 (CC3) 域是将 Atg32 集中到斑点中所必需的。我们确定了大部分 CC3 的结构，证明 CC3 形成平行的同源二聚体，其二聚体界面由少量疏水残基形成。我们进一步表明，CC3 界面不是 Atg11 二聚化所必需的，而是将 Atg32 塑造成功能性线粒体自噬起始位点和将线粒体输送到液泡所必需的。我们的研究结果表明，Atg11 自相互作用有助于将 SAR 集中为货物捕获的必要先决条件。