Structural Basis of the Differential Function of the Two C. elegans Atg8 Homologs, LGG-1 and LGG-2, in Autophagy.

Molecular cell 2015 Dec 17

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Multicellular organisms have multiple homologs of the yeast ATG8 gene, but the differential roles of these homologs in autophagy during development remain largely unknown. Here we investigated structure/function relationships in the two C. elegans Atg8 homologs, LGG-1 and LGG-2. lgg-1 is essential for degradation of protein aggregates, while lgg-2 has cargo-specific and developmental-stage-specific roles in aggregate degradation. Crystallography revealed that the N-terminal tails of LGG-1 and LGG-2 adopt the closed and open form, respectively. LGG-1 and LGG-2 interact differentially with autophagy substrates and Atg proteins, many of which carry a LIR motif. LGG-1 and LGG-2 have structurally distinct substrate binding pockets that prefer different residues in the interacting LIR motif, thus influencing binding specificity. Lipidated LGG-1 and LGG-2 possess distinct membrane tethering and fusion activities, which may result from the N-terminal differences. Our study reveals the differential function of two ATG8 homologs in autophagy during C. elegans development. Copyright © 2015 Elsevier Inc. All rights reserved.

Citation

Fan Wu, Yasunori Watanabe, Xiang-Yang Guo, Xin Qi, Peng Wang, Hong-Yu Zhao, Zheng Wang, Yuko Fujioka, Hui Zhang, Jin-Qi Ren, Tian-Cheng Fang, Yu-Xian Shen, Wei Feng, Jun-Jie Hu, Nobuo N Noda, Hong Zhang. Structural Basis of the Differential Function of the Two C. elegans Atg8 Homologs, LGG-1 and LGG-2, in Autophagy. Molecular cell. 2015 Dec 17;60(6):914-29