Anticodon Loop Structure of Torulopsis utilis tRNA^Val and Valine Acceptance

Abstract

A variant of Torulopsis utilis tRNA^Val containing base substitution (C to U) at the third letter of the anticodon has been prepared by several enzymatic reaction steps in vitro. The valine-accepting activity of this variant, tRNA^Val(IAU), was found to be decreased to a great extent. This result suggests that the third letter (C) of the anticodon of yeast tRNA^Val is strictly recognized by the Valyl-tRNA synthetase (ValRS). Combinations of 5'-half and 3'-half fragments were used to assess the importance of the anticodon loop conformation on aminoacylation. The result of this experiment indicated that the base-stacking interactions in the 3'-side region of the anticodon loop have a crucial role in the recognition of this tRNA by its cognate ValRS. In summary, both of the nucleotide sequence and the conformation of the anticodon loop are significant elements for T. utilis tRNA^Val-ValRS recognition.