著者

Kazuaki Matoba Nobuo N. Noda

出版者

The Pharmaceutical Society of Japan

雑誌

Biological and Pharmaceutical Bulletin (ISSN:09186158)

巻号頁・発行日

vol.44, no.9, pp.1337-1343, 2021-09-01 (Released:2021-09-01)

参考文献数

35

被引用文献数

3

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Autophagy is an intracellular degradation system regulating cellular homeostasis. The two ubiquitin-like modification systems named the Atg8 system and the Atg12 system are essential for autophagy. Atg8 and Atg12 are ubiquitin-like proteins covalently conjugated with a phosphatidylethanolamine (PE) and Atg5, respectively, via enzymatic reactions. The Atg8–PE conjugate binds to autophagic membranes and recruits various proteins through direct interaction, whereas the Atg12–Atg5 conjugate recognizes Atg3, the E2 enzyme for Atg8, and facilitates Atg8–PE conjugation by functioning as the E3 enzyme. Although structural and biochemical analyses have well established the Atg8-family interacting motif (AIM), studies on the interacting sequence for Atg12 are rare (only one example for human ATG12–ATG3), thereby making it challenging to define a binding motif. Here we determined the crystal structure of the plant ATG12b as a complex with the ATG12b-binding region of ATG3 and revealed that ATG12b recognizes the aspartic acid (Asp)–methionine (Met) motif in ATG3 via a hydrophobic pocket and a basic residue, which we confirmed critical for the complex formation by mutational analysis. This recognition mode is similar to that reported between human ATG12 and ATG3, suggesting that the Asp–Met sequence is a conserved Atg12-interacting motif (AIM12). These data suggest that AIM12 mediates E2-E3 interaction during Atg8 lipidation and provide structural basis for developing chemicals that regulate autophagy by targeting Atg12-family proteins.