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. 2021 Jun 21;9:685625. doi: 10.3389/fcell.2021.685625

FIGURE 1.

FIGURE 1

Binding features of ATG3/Atg3 in two conjugation systems. (A) Structure of ATG3/Atg3. (B) LC3/Atg8 transfers from ATG7/Atg7 onto ATG3/Atg3 via a transmechanism. (B1) Model representation of the Atg7∼Atg3∼Atg8 complex by aligning Atg7–Atg3 (PDB ID: 4GSL) with the Atg7CTD–Atg8 (PDB ID: 3RUI). Atg8G116 transfers from Atg7C507 to Atg3C234, where Atg3 binds with another Atg7 within an Atg7 dimer. (C) Acetylation of K19 and K48 of Atg3 promotes Atg3–Atg8 conjugate. (D) Molecular chaperone clusterin (CLU) promotes ATG3-LC3 heterocomplex stability. (E) ATG3FR binds with ATG12 conjugate facilitating LC3 lipidation. (F) ATG3 N-helix inserts highly curved membrane mediating LC3 lipidation. (G) In yeast, the interaction between the loop (blue) containing the catalytic Cys234 and helix G (brown) in Atg3 makes Cys234 face away from Thr213, which suppresses Atg3 conjugase activity. Atg12–Atg5 leads to the reorientation of Cys234 by some unknown means, and then Cys234 faces to Thr213 to facilitate the Atg8 lipidation. (H) N-terminal domain of Atg3 can increase local PE density on the membrane.