Recognition of the Nucleoside in the First Position of the Anticodon of Isoleucine tRNA by Isoleucyl-tRNA Synthetase from Escherichia Coli

Abstract
Escherichia coli tRNAIle 1 prepared in vitro by T7 RNA polymerase transcription was found to be charged with isoleucine by E. coli isoleucyl-tRNA synthetase (IleRS). Replacement of G in the first position of the anticodon with U, C, or A resulted in complete loss of isoleucine-accepting activity. This indicates that IleRS strictly recognizes the structural feature of guanosine in this position of tRNAIle 1 which is common to that of lysidine in E. coli tRNAIle 2.