title: A present-day aminoacyl-tRNA synthetase with ancestral editing properties.
abstract: Leucyl-, isoleucyl-, and valyl-tRNA synthetases form a subgroup of related aminoacyl-tRNA synthetases that attach similar amino acids to their cognate tRNAs. To prevent amino acid misincorporation during translation, these enzymes also hydrolyze mischarged tRNAs through a post-transfer editing mechanism. Here we show that LeuRS from the deep-branching bacterium Aquifex aeolicus edits the complete set of aminoacylated tRNAs generated by the three enzymes: Ile-tRNA(Ile), Val-tRNA(Ile), Val-tRNA(Val), Thr-tRNA(Val), and Ile-tRNA(Leu). This unusual enlarged editing property was studied in a model of a primitive editing system containing a composite minihelix carrying the triple leucine, isoleucine, and valine identity mimicking the primitive tRNA precursor. We found that the freestanding LeuRS editing domain can edit this precursor in contrast to IleRS and ValRS editing domains. These results suggest that A. aeolicus LeuRS carries editing properties that seem more primitive than those of IleRS and ValRS. They suggest that the A. aeolicus editing domain has preserved the ambiguous editing property from the ancestral common editing domain or, alternatively, that this plasticity results from a specific metabolic adaptation.
authors.affiliation: State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, Shanghai, People's Republic of China.
authors.forename: Bin
authors.initials: B
authors.lastname: Zhu
authors.forename: Ming-Wei
authors.initials: MW
authors.lastname: Zhao
authors.forename: Gilbert
authors.initials: G
authors.lastname: Eriani
authors.forename: En-Duo
authors.initials: ED
authors.lastname: Wang
mesh_terms: D001419:Bacteria / Q000201:enzymology* / Q000235:genetics; D001483:Base Sequence; D019143:Evolution, Molecular; D007533:Isoleucine-tRNA Ligase / Q000737:chemistry / Q000502:physiology; D007935:Leucine-tRNA Ligase / Q000737:chemistry / Q000502:physiology*; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D017393:RNA Editing; D012329:RNA, Bacterial / Q000378:metabolism*; D013379:Substrate Specificity; D046249:Transfer RNA Aminoacylation; D014637:Valine-tRNA Ligase / Q000737:chemistry / Q000502:physiology
chemical_list: D012329:RNA, Bacterial; D007935:Leucine-tRNA Ligase; D007533:Isoleucine-tRNA Ligase; D014637:Valine-tRNA Ligase