title: LC3 and GATE-16 N termini mediate membrane fusion processes required for autophagosome biogenesis.
abstract: Autophagy is a unique membrane trafficking pathway describing the formation and targeting of double membrane autophagosomes to the vacuole/lysosome. The biogenesis of autophagosomes and their delivery to the vacuole/lysosome depend on multiple membrane fusion events. Using a cell-free system, we have investigated the ability of LC3 and GATE-16, two mammalian Atg8 orthologs, to mediate membrane fusion. We found that both proteins promote tethering and membrane fusion, mediated by the proteins' N-terminal α helices. We further show that short, 10 amino acid long synthetic peptides derived from the N terminus of LC3 or GATE-16 are sufficient to promote membrane fusion. Our data indicate that the fusion activity of LC3 is mediated by positively charged amino acids, whereas the activity of GATE-16 is mediated by hydrophobic interactions. Finally, we demonstrate that LC3 and GATE-16 N termini in general and specific residues needed for the fusion activity are essential for the proteins role in autophagosome biogenesis.
authors.affiliation: Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Hilla
authors.initials: H
authors.lastname: Weidberg
authors.forename: Tomer
authors.initials: T
authors.lastname: Shpilka
authors.forename: Elena
authors.initials: E
authors.lastname: Shvets
authors.forename: Adi
authors.initials: A
authors.lastname: Abada
authors.forename: Frida
authors.initials: F
authors.lastname: Shimron
authors.forename: Zvulun
authors.initials: Z
authors.lastname: Elazar
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001343:Autophagy; D000071190:Autophagy-Related Protein 8 Family; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D006367:HeLa Cells; D006801:Humans; D008561:Membrane Fusion / Q000235:genetics; D008840:Microfilament Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010588:Phagosomes / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000071190:Autophagy-Related Protein 8 Family; C498698:GABARAPL2 protein, human; C477012:MAP1LC3A protein, human; D008840:Microfilament Proteins; D008869:Microtubule-Associated Proteins