Vesicle tethering and fusion promoted by LC3/GABARAP proteins is modulated by the ATG12-ATG5-ATG16L1 complex

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 sugge...

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Bibliographic Details
Published in:Autophagy 2023-10, Vol.19 (10), p.2827-2829
Main Authors: Iriondo, Marina N., Alonso, Alicia
Format: Article
Language:English
Subjects:
Apoptosis Regulatory Proteins
ATG12-ATG5-ATG16L1
ATG8
Autophagic Punctum
autophagosome expansion
Autophagosomes - metabolism
Autophagy
Autophagy proteins
Autophagy-Related Protein 12
Autophagy-Related Protein 5
Autophagy-Related Proteins - metabolism
E3 complex
Humans
LC3/GABARAP
Lipids
Microtubule-Associated Proteins - metabolism
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Summary: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.
ISSN:1554-8627
1554-8635
DOI:10.1080/15548627.2023.2202557