Structural basis for the specificity and catalysis of human Atg4B responsible for mammalian autophagy.
Reversible modification of Atg8 with phosphatidylethanolamine is crucial for autophagy, the bulk degradation system conserved in eukaryotic cells. Atg4 is a novel cysteine protease that processes and deconjugates Atg8. Herein, we report the crystal structure of human Atg4B (HsAtg4B) at 1.9-A resolution. Despite no obvious sequence homology with known proteases, the structure of HsAtg4B shows a classical papain-like fold. In addition to the papain fold region, HsAtg4B has a small alpha/beta-fold domain. This domain is thought to be the binding site for Atg8 homologs. The active site cleft of HsAtg4B is masked by a loop (residues 259-262), implying a conformational change upon substrate binding. The structure and in vitro mutational analyses provide the basis for the specificity and catalysis of HsAtg4B. This will enable the design of Atg4-specific inhibitors that block autophagy.
Sugawara
Kenji
K
Department of Structural Biology, Graduate School of Pharmaceutical Sciences, Hokkaido University, N-12, W-6, Kita-ku, Sapporo 060-0812, Japan.
Suzuki
Nobuo N
NN
Fujioka
Yuko
Y
Mizushima
Noboru
N
Ohsumi
Yoshinori
Y
Inagaki
Fuyuhiko
F
D000595:Amino Acid Sequence; D001343:Autophagy; D000071183:Autophagy-Related Proteins; D001665:Binding Sites; D002384:Catalysis; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D003546:Cysteine Endopeptidases / Q000737:chemistry* / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009154:Mutation; D010206:Papain / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D013379:Substrate Specificity
D000071183:Autophagy-Related Proteins; D005982:Glutathione Transferase; C507524:ATG4B protein, human; C582881:Atg4b protein, mouse; D003546:Cysteine Endopeptidases; D010206:Papain