Here we present a new regulatory mechanism of autophagy, which influences the conjugation and de-conjugation of autophagy modifiers to autophagosomes. TBK1 phosphorylates LC3C and GABARAP-L2, which impedes LC3 binding to the processing enzyme ATG4.

https://doi.org/10.15252/embr.201948317

• TBK1 phosphorylates autophagy modifiers LC3C and GABARAP-L2 on surface-exposed serine-residues.
• GABARAP-L2 S87/88-PO₄ and LC3C S93/96-PO₄ impedes binding to the ATG4 protease.
• Phosphorylated LC3C/GABARAP-L2 are protected from ATG4-mediated premature removal from autophagosomes.