Structure of the ribotrinucleoside diphosphate codon UpUpC bound to tRNA Phe from yeast : A time-dependent transferred nuclear overhauser enhancement study

Abstract

The structure of the ribotrinucleoside diphosphate UpUpC, the codon for phenylalanine, bound to yeast tRNA Phe in solution is elucidated using time-dependent proton-proton transferred nuclear Overhauser enhancement measurements to determine distances between bound ligand protons. The glycosidic bond and ribose conformations are low anti and 3′- endo, respectively, typical of an A-RNA type structure. The main chain torsion angles are all within the range of those expected for A-RNA but small differences from those in conventional A-RNA 11 result in a special structure with a larger rotation per residue (40 to 45 ° compared to 32.7 ° in R-RNA 11) and almost perfect stacking of the bases. These two structural features, which are similar to those found in the anticodon triplet of the monoclinic crystal form of tRNA Phe, can account for the known greater stability of the codon-anticodon complex relative to an equivalent double helical RNA trimer with a conventional A-RNA structure.