Iriondo MN, Alonso A. Vesicle tethering and fusion promoted by LC3/GABARAP proteins is modulated by the ATG12-ATG5-ATG16L1 complex.
Autophagy 2023;
19:2827-2829. [PMID:
37062893 PMCID:
PMC10472856 DOI:
10.1080/15548627.2023.2202557]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 04/05/2023] [Accepted: 04/05/2023] [Indexed: 04/18/2023] Open
Abstract
Recently, we have examined the membrane anchoring and subsequent lipidation of six members of the LC3/GABARAP protein family, together with their ability to promote membrane tethering and fusion. GABARAP and GABARAPL1 showed the highest activities. Differences found within LC3/GABARAP proteins suggested the existence of a lipidation threshold as a requisite for tethering and inter-vesicular lipid mixing. The presence of ATG12-ATG5-ATG16L1 (E3 in short) increased and accelerated LC3/GABARAP lipidation and subsequent vesicle tethering. However, E3 hampered LC3/GABARAP capacity to induce inter-vesicular lipid mixing and/or fusion. Our results suggest a model in which, together with the recently described inter-membrane lipid transfer mechanism, LC3/GABARAP could help in the phagophore expansion process through their ability to tether and fuse vesicles. The growing regions would be areas where the LC3/GABARAP proteins could be lipidated in the absence of E3, or else an independent regulatory mechanism would allow lipid/vesicle incorporation and phagophore growth when E3 was present.Abbreviations: Atg/ATG: autophagy-related protein (in yeast/human); E3: ATG12-ATG5-ATG16L1 complex; GABARAP: gamma-aminobutyric acid receptor associated protein; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3.
Collapse