Autophagosome targeting and membrane curvature sensing by Barkor/Atg14(L)
- 25 April 2011
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 108 (19), 7769-7774
- https://doi.org/10.1073/pnas.1016472108
Abstract
The class III phosphatidylinositol 3-kinase (PI3KC3) is crucial for autophagosome biogenesis. It has been long speculated to nucleate the autophagosome membrane, but the biochemical mechanism of such nucleation activity remains unsolved. We recently identified Barkor/Atg14(L) as the targeting factor for PI3KC3 to autophagosome membrane. Here, we show that we have characterized the region of Barkor/Atg14(L) required for autophagosome targeting and identified the BATS [Barkor/Atg14(L) autophagosome targeting sequence] domain at the carboxyl terminus of Barkor. Bioinformatics and mutagenesis analyses revealed that the BATS domain binds to autophagosome membrane via the hydrophobic surface of an intrinsic amphipathic alpha helix. BATS puncta overlap with Atg16 and LC3, and partially with DFCP1, in a stress-inducible manner. Ectopically expressed BATS accumulates on highly curved tubules that likely represent intermediate autophagic structures. PI3KC3 recruitment and autophagy stimulation by Barkor/Atg14(L) require the BATS domain. Furthermore, our biochemical analyses indicate that the BATS domain directly binds to the membrane, and it favors membrane composed of phosphatidylinositol 3-phosphate [PtdIns(3)P] and phosphatidylinositol 4,5-biphosphate [PtdIns(4,5)P2]. By binding preferentially to curved membranes incorporated with PtdIns(3)P but not PtdIns(4,5)P2, the BATS domain is capable of sensing membrane curvature. Thus, we propose a novel model of PI3KC3 autophagosome membrane nucleation in which its autophagosome-specific adaptor, Barkor, accumulates on highly curved PtdIns(3)P enriched autophagic membrane via its BATS domain to sense and maintain membrane curvature.Keywords
This publication has 39 references indexed in Scilit:
- Membrane Fusion: Five Lipids, Four SNAREs, Three Chaperones, Two Nucleotides, and a Rab, All Dancing in a Ring on Yeast VacuolesAnnual Review of Cell and Developmental Biology, 2010
- Rubicon controls endosome maturation as a Rab7 effectorProceedings of the National Academy of Sciences, 2010
- Selective Transport of α-Mannosidase by Autophagic PathwaysJournal of Biological Chemistry, 2010
- Development by Self-DigestionDevelopmental Cell, 2004
- BAR Domains as Sensors of Membrane Curvature: The Amphiphysin BAR StructureScience, 2004
- Coat control by curvatureNature, 2003
- Curvature of clathrin-coated pits driven by epsinNature, 2002
- Molecular dissection of autophagy: two ubiquitin-like systemsNature Reviews Molecular Cell Biology, 2001
- Dissection of Autophagosome Formation Using Apg5-Deficient Mouse Embryonic Stem CellsThe Journal of cell biology, 2001
- Simultaneous Binding of PtdIns(4,5)P 2 and Clathrin by AP180 in the Nucleation of Clathrin Lattices on MembranesScience, 2001