ATG4B contains a C-terminal LIR motif important for binding and efficient cleavage of mammalian orthologs of yeast Atg8
ATG4B contains a C-terminal LIR motif important for binding and efficient cleavage of mammalian orthologs of yeast Atg8
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DOI：
10.1080/15548627.2017.1287651
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发表时间：
2017-01-01
期刊：
影响因子：
13.3
通讯作者：
Johansen, Terje
中科院分区：
文献类型：
--
作者：
Rasmussen, Mads Skytte;Mouilleron, Sephane;Johansen, Terje
半胱氨酸蛋白酶ATG 4 B切除酵母Atg 8的直系同源物和旁系同源物LC 3和GABARAP亚家族的蛋白质的无活性前体的一个或多个C末端残基，以暴露在自噬体形成期间与磷脂酰乙醇胺缀合的C末端甘氨酸。我们发现，ATG 4 B包含一个C-末端LC 3相互作用区（LIR）基序的有效结合和裂解的LC 3和GABARAP蛋白的重要。我们解决了GABARAPL 1-ATG 4 B C-末端LIR复合物的晶体结构。使用特定点突变体的结构分析和体外结合测定清楚地表明，ATG 4 B LIR通过静电、芳香族HP 1和疏水性HP 2口袋相互作用结合。这些相互作用和催化位点-底物相互作用都有助于LC 3或GABARAP与ATG 4 B之间的结合。我们还揭示了ATG 4 B在稳定GABARAP和GABARAPL 1的非脂化形式中的意想不到的作用。在小鼠胚胎成纤维细胞（MEF）atg 4 b基因敲除细胞，GABARAP和GABARAPL 1是不稳定的，被蛋白酶体降解。引人注目的是，ATG 4 B的LIR基序是稳定细胞中GABARAP和GABARAPL 1的非脂化形式所必需的。
The cysteine protease ATG4B cleaves off one or more C-terminal residues of the inactive proform of proteins of the ortholog and paralog LC3 and GABARAP subfamilies of yeast Atg8 to expose a C-terminal glycine that is conjugated to phosphatidylethanolamine during autophagosome formation. We show that ATG4B contains a C-terminal LC3-interacting region (LIR) motif important for efficient binding to and cleavage of LC3 and GABARAP proteins. We solved the crystal structures of the GABARAPL1-ATG4B C-terminal LIR complex. Analyses of the structures and in vitro binding assays, using specific point mutants, clearly showed that the ATG4B LIR binds via electrostatic-, aromatic HP1 and hydrophobic HP2 pocket interactions. Both these interactions and the catalytic site-substrate interaction contribute to binding between LC3s or GABARAPs and ATG4B. We also reveal an unexpected role for ATG4B in stabilizing the unlipidated forms of GABARAP and GABARAPL1. In mouse embryonic fibroblast (MEF) atg4b knockout cells, GABARAP and GABARAPL1 were unstable and degraded by the proteasome. Strikingly, the LIR motif of ATG4B was required for stabilization of the unlipidated forms of GABARAP and GABARAPL1 in cells.