The mammalian Atg8 family proteins are central drivers of autophagy and contain six members, classified into the LC3 and GABARAP subfamilies. Due to their high sequence similarity and consequent functional overlaps, it is difficult to delineate specific functions of Atg8 proteins in autophagy. Here we discover a super-strong GABARAP-selective inhibitory peptide harbored in 270/480 kDa ankyrin-G and a super-potent pan-Atg8 inhibitory peptide from 440 kDa ankyrin-B. Structural studies elucidate the mechanism governing the Atg8 binding potency and selectivity of the peptides, reveal a general Atg8-binding sequence motif, and allow development of a more GABARAP-selective inhibitory peptide. These peptides effectively blocked autophagy when expressed in cultured cells. Expression of these ankyrin-derived peptides in Caenorhabditis elegans also inhibited autophagy, causing accumulation of the p62 homolog SQST-1, delayed development and shortened life span. Thus, these genetically encodable autophagy inhibitory peptides can be used to occlude autophagy spatiotemporally in living animals.

哺乳动物Atg8家族蛋白是自噬的主要驱动力，包含六个成员，分为LC3和GABARAP亚家族。由于它们的高度序列相似性以及随之而来的功能重叠，因此很难在自噬中描述Atg8蛋白的特定功能。在这里，我们发现了在270/480 kDa锚蛋白G中具有超强GABARAP选择性抑制肽和在440 kDa锚蛋白B中具有超强泛Atg8抑制肽。结构研究阐明了控制肽Atg8结合力和选择性的机制，揭示了一般的Atg8结合序列基序，并允许开发更具GABARAP选择性的抑制性肽。当在培养的细胞中表达时，这些肽有效地阻断了自噬。这些锚蛋白衍生肽的表达秀丽隐杆线虫也抑制自噬，引起p62同系物SQST-1的积累，延迟发育并缩短寿命。因此，这些可遗传编码的自噬抑制肽可用于在活体动物中时空阻塞自噬。