Studies on T. utilis tRNATyr Variants with Enzymatically Altered D-Loop Sequences. I. Deletion of the Conserved Sequence Gm-G and Its Effects on Aminoacylation and Conformation1

Publisher Website
Google Scholar
Abstract
Variants of T. utilis tRNATyr containing deletions or substitutions of nucleotides in the D-loop region have been prepared by several enzymatic reaction steps in vitro. Although these variants lack the “conserved” nucleotides Gm18-G19 in their D-loop, their tyrosine-accepting capacities are indistinguishable from that of the native tRNATyr. Thermal denaturation studies with tRNATyr variants lacking the Gm18-G19 sequence have revealed a biphasic nature of the melting profile, suggesting the loss of tertiary interactions between Gm18-G19 and somewhere in the molecule (probably in the TψC-loop region). These results indicate that nucleotide sequences around Gm18-G19(i.e. D16-D-Gm-G19 or Gm18-G-D-D21) themselves are not essential sites for the recognition of tRNATyr by T. utilis tyrosyl-tRNA synthetase and that tRNATyr variants with an apparently “relaxed” conformation still have full aminoacylation capacities at around 30°C.