TY - JOUR
T1 - Arginine68 is an essential residue for the C-terminal cleavage of human Atg8 family proteins
AU - Liu, Chao
AU - Ma, Haijie
AU - Wu, Jiaxue
AU - Huang, Qiang
AU - Liu, Jun O.
AU - Yu, Long
N1 - Funding Information:
We thank Dr. Jianping Ding (Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China) and Dr. Yanhui Xu (Institute of Biomedical Sciences, Fudan University, Shanghai, China) for faithful advices of LC3B structure analysis, Dr. Xianmei Yang for initial paper draft preparation, Yefang Gong and Yunmin Xu for technical assistance. The authors are grateful to Henry Kuang and Zhonghao Wang for proof reading. This work was supported by the National 973 program of China (2004CB518605), the National 863 project of China (2006AA020501), the National Key Sci-Tech Special Project of China (2008ZX10002-020), the Project of the Shanghai Municipal Science and Technology Commission (03dz14086) and the National Natural Science foundation of China (30024001, 30771188).
PY - 2013/5/30
Y1 - 2013/5/30
N2 - Background: Autophagy is a conserved cellular process that degrades and recycles cytoplasmic components via a lysosomal pathway. The phosphatidylethanolamine (PE)-conjugation of the Atg8 protein plays an important role in the yeast autophagy process. In humans, six Atg8 homologs, including MAP1LC3A, MAP1LC3B, MAP1LC3C (refer to LC3A, LC3B, and LC3C hereafter), GABARAP, GABARAPL1, and GABARAPL2 have been reported. All of them can be conjugated to PE through a ubiquitin-like conjugation system, and be located to autophagosomes.Results: In this study, we found 3 new alternative splicing isoforms in LC3B, GABARAP, and GABARAPL1, (designated as LC3B-a, GABARAP-a and GABARAPL1-a, respectively). None of them can go through the PE-conjugation process and be located to autophagosomes. Interestingly, compared with LC3B, LC3B-a has a single amino acid (Arg68) deletion due to the NAGNAG alternative splicing in intron 3. Through structural simulations, we found that the C-terminal tail of LC3B-a is less mobile than that of LC3B, thus affecting its C-terminal cleavage by human ATG4 family proteins. Furthermore, we found that Arg68 is an essential residue facilitating the interaction between human Atg8 family proteins and ATG4B by forming a salt bridge with Asp171 of ATG4B. Depletion of this salt bridge reduces autophagosomes formation and autophagic flux under both normal and nutrition starvation conditions.Conclusions: These results suggest Arg68 is an essential residue for the C-terminal cleavage of Atg8 family proteins during the autophagy process.
AB - Background: Autophagy is a conserved cellular process that degrades and recycles cytoplasmic components via a lysosomal pathway. The phosphatidylethanolamine (PE)-conjugation of the Atg8 protein plays an important role in the yeast autophagy process. In humans, six Atg8 homologs, including MAP1LC3A, MAP1LC3B, MAP1LC3C (refer to LC3A, LC3B, and LC3C hereafter), GABARAP, GABARAPL1, and GABARAPL2 have been reported. All of them can be conjugated to PE through a ubiquitin-like conjugation system, and be located to autophagosomes.Results: In this study, we found 3 new alternative splicing isoforms in LC3B, GABARAP, and GABARAPL1, (designated as LC3B-a, GABARAP-a and GABARAPL1-a, respectively). None of them can go through the PE-conjugation process and be located to autophagosomes. Interestingly, compared with LC3B, LC3B-a has a single amino acid (Arg68) deletion due to the NAGNAG alternative splicing in intron 3. Through structural simulations, we found that the C-terminal tail of LC3B-a is less mobile than that of LC3B, thus affecting its C-terminal cleavage by human ATG4 family proteins. Furthermore, we found that Arg68 is an essential residue facilitating the interaction between human Atg8 family proteins and ATG4B by forming a salt bridge with Asp171 of ATG4B. Depletion of this salt bridge reduces autophagosomes formation and autophagic flux under both normal and nutrition starvation conditions.Conclusions: These results suggest Arg68 is an essential residue for the C-terminal cleavage of Atg8 family proteins during the autophagy process.
KW - Alternative splicing
KW - Atg8
KW - Autophagy
KW - MAP1LC3B
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U2 - 10.1186/1471-2121-14-27
DO - 10.1186/1471-2121-14-27
M3 - Article
C2 - 23721406
AN - SCOPUS:84878263360
VL - 14
JO - BMC Cell Biology
JF - BMC Cell Biology
SN - 1471-2121
IS - 1
M1 - 27
ER -