5knn | pdb_00005knn
Evolutionary gain of alanine mischarging to non-cognate tRNAs with a G4:U69 base pair
Structural highlights
DiseaseSYAC_HUMAN Autosomal dominant Charcot-Marie-Tooth disease type 2N. The disease is caused by mutations affecting the gene represented in this entry. The disease is caused by mutations affecting the gene represented in this entry. FunctionSYAC_HUMAN Catalyzes the attachment of alanine to tRNA(Ala) in a two-step reaction: alanine is first activated by ATP to form Ala-AMP and then transferred to the acceptor end of tRNA(Ala). Also edits incorrectly charged tRNA(Ala) via its editing domain.[HAMAP-Rule:MF_03133] Publication Abstract from PubMedFidelity of translation, which is predominately dictated by the accuracy of aminoacyl-tRNA synthetases in pairing amino acids with correct tRNAs, is of central importance in biology. Yet, deliberate modifications of translational fidelity can be beneficial. Here we found human and not E. coli AlaRS has an intrinsic capacity for mis-pairing alanine onto non-alanyl-tRNAs including tRNACys. Consistently, a cysteine-to-alanine substitution was found in a reporter protein expressed in human cells. All human AlaRS-mischarged tRNAs have a G4:U69 base pair in the acceptor stem. The base pair is required for the mischarging. By solving the crystal structure of human AlaRS and comparing it to that of E. coli AlaRS, we identified a key sequence divergence between eukaryotes and bacteria that influences mischarging. Thus, the expanded tRNA specificity of AlaRS appears to be an evolutionary gain-of-function to provide posttranscriptional alanine substitutions in eukaryotic proteins for potential regulations. Evolutionary gain of alanine mischarging to non-cognate tRNAs with a G4:U69 base pair.,Sun L, Gomes AC, He W, Zhou H, Wang X, Pan DW, Schimmel P, Pan T, Yang XL J Am Chem Soc. 2016 Sep 13. PMID:27622773[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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