Leucyl-tRNA synthetase from the ancestral bacterium Aquifex aeolicus contains relics of synthetase evolution.
The editing reactions catalyzed by aminoacyl-tRNA synthetases are critical for the faithful protein synthesis by correcting misactivated amino acids and misaminoacylated tRNAs. We report that the isolated editing domain of leucyl-tRNA synthetase from the deep-rooted bacterium Aquifex aeolicus (alphabeta-LeuRS) catalyzes the hydrolytic editing of both mischarged tRNA(Leu) and minihelix(Leu). Within the domain, we have identified a crucial 20-amino-acid peptide that confers editing capacity when transplanted into the inactive Escherichia coli LeuRS editing domain. Likewise, fusion of the beta-subunit of alphabeta-LeuRS to the E. coli editing domain activates its editing function. These results suggest that alphabeta-LeuRS still carries the basic features from a primitive synthetase molecule. It has a remarkable capacity to transfer autonomous active modules, which is consistent with the idea that modern synthetases arose after exchange of small idiosyncratic domains. It also has a unique alphabeta-heterodimeric structure with separated catalytic and tRNA-binding sites. Such an organization supports the tRNA/synthetase coevolution theory that predicts sequential addition of tRNA and synthetase domains.
Zhao
Ming-Wei
MW
State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Shanghai, PR China.
Zhu
Bin
B
Hao
Rui
R
Xu
Min-Gang
MG
Eriani
Gilbert
G
Wang
En-Duo
ED
D000595:Amino Acid Sequence; D001419:Bacteria / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D019143:Evolution, Molecular; D007935:Leucine-tRNA Ligase / Q000235:genetics* / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis / Q000235:genetics*; D017434:Protein Structure, Tertiary / Q000235:genetics; D016415:Sequence Alignment
D007935:Leucine-tRNA Ligase