Calpain Cleaves Most Components in the Multiple Aminoacyl-tRNA Synthetase Complex and Affects Their Functions.
Nine aminoacyl-tRNA synthetases (aaRSs) and three scaffold proteins form a super multiple aminoacyl-tRNA synthetase complex (MSC) in the human cytoplasm. Domains that have been added progressively to MSC components during evolution are linked by unstructured flexible peptides, producing an elongated and multiarmed MSC structure that is easily attacked by proteases in vivo. A yeast two-hybrid screen for proteins interacting with LeuRS, a representative MSC member, identified calpain 2, a calcium-activated neutral cysteine protease. Calpain 2 and calpain 1 could partially hydrolyze most MSC components to generate specific fragments that resembled those reported previously. The cleavage sites of calpain in ArgRS, GlnRS, and p43 were precisely mapped. After cleavage, their N-terminal regions were removed. Sixty-three amino acid residues were removed from the N terminus of ArgRS to form ArgRSΔN63; GlnRS formed GlnRSΔN198, and p43 formed p43ΔN106. GlnRSΔN198 had a much weaker affinity for its substrates, tRNA(Gln) and glutamine. p43ΔN106 was the same as the previously reported p43-derived apoptosis-released factor. The formation of p43ΔN106 by calpain depended on Ca(2+) and could be specifically inhibited by calpeptin and by RNAi of the regulatory subunit of calpain in vivo. These results showed, for the first time, that calpain plays an essential role in dissociating the MSC and might regulate the canonical and non-canonical functions of certain components of the MSC.
From the State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China, University of Chinese Academy of Sciences, Beijing 100039, China.
Hui-Yan
HY
Lei
From the State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China, University of Chinese Academy of Sciences, Beijing 100039, China.
Xiao-Long
XL
Zhou
From the State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China, University of Chinese Academy of Sciences, Beijing 100039, China.
Zhi-Rong
ZR
Ruan
From the State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China, University of Chinese Academy of Sciences, Beijing 100039, China, The School of Life Science and Technology, ShanghaiTech University, 319 Yue Yang Road, Shanghai 200031, China, and.
Wei-Cheng
WC
Sun
Architecture et Réactivité de l'ARN, Université de Strasbourg, UPR9002 CNRS, Institut de Biologie Moléculaire et Cellulaire, 15 rue René Descartes, 67084 Strasbourg Cedex, France.
Gilbert
G
Eriani
From the State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China, University of Chinese Academy of Sciences, Beijing 100039, China, The School of Life Science and Technology, ShanghaiTech University, 319 Yue Yang Road, Shanghai 200031, China, and edwang@sibcb.ac.cn.
En-Duo
ED
Wang
D000595:Amino Acid Sequence; D000604:Amino Acyl-tRNA Synthetases / Q000737:chemistry / Q000378:metabolism*; D002154:Calpain / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D059748:Proteolysis; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D011994:Recombinant Proteins; D002154:Calpain; D000604:Amino Acyl-tRNA Synthetases
aminoacyl tRNA synthetase; aminoacylation; calpain; protein fragments; protein secretion; proteolysis; stress