Regulation of LC3 lipidation by the autophagy-specific class III phosphatidylinositol-3 kinase complex
Journal Article
·
· Molecular Biology of the Cell
- Univ. of California, Berkeley, CA (United States). Dept. of Molecular and Cell Biology; Univ. of California, Berkeley, CA (United States). Howard Hughes Medical Inst.; DOE/OSTI
- Univ. of California, Berkeley, CA (United States). Dept. of Molecular and Cell Biology; Univ. of California, Berkeley, CA (United States). Howard Hughes Medical Inst.
- Univ. of California, Berkeley, CA (United States). Dept. of Molecular and Cell Biology; Univ. of California, Berkeley, CA (United States). California Inst. for Quantitative Biosciences; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Biophysics and Integrated Bioimaging Division
- Univ. of California, Berkeley, CA (United States). Dept. of Molecular and Cell Biology
Autophagy is a conserved eukaryotic pathway critical for cellular adaptation to changes in nutrition levels and stress. The class III phosphatidylinositol (PI)3-kinase complexes I and II (PI3KC3-C1 and -C2) are essential for autophagosome initiation and maturation, respectively, from highly curved vesicles. We used a cell-free reaction that reproduces a key autophagy initiation step, LC3 lipidation, as a biochemical readout to probe the role of autophagy-related gene (ATG)14, a PI3KC3-C1-specific subunit implicated in targeting the complex to autophagy initiation sites. We reconstituted LC3 lipidation with recombinant PI3KC3-C1, -C2, or various mutant derivatives added to extracts derived from a CRISPR/Cas9-generated ATG14-knockout cell line. Both complexes C1 and C2 require the C-terminal helix of VPS34 for activity on highly curved membranes. However, only complex C1 supports LC3 lipidation through the curvature-targeting amphipathic lipid packing sensor (ALPS) motif of ATG14. Furthermore, the ALPS motif and VPS34 catalytic activity are required for downstream recruitment of WD-repeat domain phosphoinositide-interacting protein (WIPI)2, a protein that binds phosphatidylinositol 3-phosphate and its product phosphatidylinositol 3, 5-bisphosphate, and a WIPI-binding protein, ATG2A, but do not affect membrane association of ATG3 and ATG16L1, enzymes contributing directly to LC3 lipidation. These data reveal the nuanced role of the ATG14 ALPS in membrane curvature sensing, suggesting that the ALPS has additional roles in supporting LC3 lipidation.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- Grant/Contract Number:
- AC02-05CH11231
- OSTI ID:
- 1625250
- Journal Information:
- Molecular Biology of the Cell, Journal Name: Molecular Biology of the Cell Journal Issue: 9 Vol. 30; ISSN 1059-1524
- Publisher:
- American Society for Cell BiologyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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