Figure 10.

Graphical Model of ABA-Triggered Induction of Autophagy Mediated by Posttranslational Modification of ATG4.

Under basal conditions, intracellular sulfide maintains high levels of persulfidation of the ATG4 pool, which inhibits the proteolytic activity of the enzyme for ATG8 C-terminal processing. An increase in the intracellular level of ABA transiently decreases the level of persulfidation of the ATG4 population activating the protease activity of the enzyme and the processing of ATG8 that can be further lipidated to progress autophagy. Yellow circles represent ATG8 protein with or without the processed C terminus (represented as X). Blue semicircles represent persulfidated ATG4 at the thiol group of Cys170 residue. Blue Pacman symbols represent ATG4 with reduced thiol group of Cys170 residue. The conjugation process of ATG8 with PE, and autophagosome initiation and closure are also shown.