Structural basis for membrane recruitment of ATG16L1 by WIPI2 in autophagy.
Autophagy is a cellular process that degrades cytoplasmic cargo by engulfing it in a double-membrane vesicle, known as the autophagosome, and delivering it to the lysosome. The ATG12-5-16L1 complex is responsible for conjugating members of the ubiquitin-like ATG8 protein family to phosphatidylethanolamine in the growing autophagosomal membrane, known as the ... phagophore. ATG12-5-16L1 is recruited to the phagophore by a subset of the phosphatidylinositol 3-phosphate-binding seven-bladedss -propeller WIPI proteins. We determined the crystal structure of WIPI2d in complex with the WIPI2 interacting region (W2IR) of ATG16L1 comprising residues 207-230 at 1.85 A resolution. The structure shows that the ATG16L1 W2IR adopts an alpha helical conformation and binds in an electropositive and hydrophobic groove between WIPI2 ss-propeller blades 2 and 3. Mutation of residues at the interface reduces or blocks the recruitment of ATG12-5-16 L1 and the conjugation of the ATG8 protein LC3B to synthetic membranes. Interface mutants show a decrease in starvation-induced autophagy. Comparisons across the four human WIPIs suggest that WIPI1 and 2 belong to a W2IR-binding subclass responsible for localizing ATG12-5-16 L1 and driving ATG8 lipidation, whilst WIPI3 and 4 belong to a second W34IR-binding subclass responsible for localizing ATG2, and so directing lipid supply to the nascent phagophore. The structure provides a framework for understanding the regulatory node connecting two central events in autophagy initiation, the action of the autophagic PI 3-kinase complex on the one hand and ATG8 lipidation on the other.
Mesh Terms:
Autophagosomes, Autophagy, Autophagy-Related Protein 8 Family, Autophagy-Related Proteins, Crystallography, HeLa Cells, Humans, Hydrophobic and Hydrophilic Interactions, Intracellular Membranes, Membrane Proteins, Models, Molecular, Phosphate-Binding Proteins, Phosphatidylinositol 3-Kinase, Point Mutation, Protein Conformation, alpha-Helical, Protein Transport, Signal Transduction, Structure-Activity Relationship
Autophagosomes, Autophagy, Autophagy-Related Protein 8 Family, Autophagy-Related Proteins, Crystallography, HeLa Cells, Humans, Hydrophobic and Hydrophilic Interactions, Intracellular Membranes, Membrane Proteins, Models, Molecular, Phosphate-Binding Proteins, Phosphatidylinositol 3-Kinase, Point Mutation, Protein Conformation, alpha-Helical, Protein Transport, Signal Transduction, Structure-Activity Relationship
Elife
Date: Dec. 10, 2020
PubMed ID: 34505572
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