Publication Abstract from PubMed
Ligation of tRNAs with their cognate amino acids, by aminoacyl-tRNA synthetases, establishes the genetic code. Throughout evolution, tRNA(Ala) selection by alanyl-tRNA synthetase (AlaRS) has depended predominantly on a single wobble base pair in the acceptor stem, G3*U70, mainly on the kcat level. Here we report the crystal structures of an archaeal AlaRS in complex with tRNA(Ala) with G3*U70 and its A3*U70 variant. AlaRS interacts with both the minor- and the major-groove sides of G3*U70, widening the major groove. The geometry difference between G3*U70 and A3*U70 is transmitted along the acceptor stem to the 3'-CCA region. Thus, the 3'-CCA region of tRNA(Ala) with G3*U70 is oriented to the reactive route that reaches the active site, whereas that of the A3*U70 variant is folded back into the non-reactive route. This novel mechanism enables the single wobble pair to dominantly determine the specificity of tRNA selection, by an approximate 100-fold difference in kcat.
The selective tRNA aminoacylation mechanism based on a single G*U pair.,Naganuma M, Sekine S, Chong YE, Guo M, Yang XL, Gamper H, Hou YM, Schimmel P, Yokoyama S Nature. 2014 Jun 26;510(7506):507-11. doi: 10.1038/nature13440. Epub 2014 Jun 11. PMID:24919148[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
