FOOTPRINTING OF TRNA(PHE) TRANSCRIPTS FROM THERMUS-THERMOPHILUS HB8 WITH THE HOMOLOGOUS PHENYLATANYL-TRANSFER-RNA SYNTHETASE REVEALS A NOVEL MODE OF INTERACTION

The phosphates of the tRNA(Phe) transcript from Thermus thermophilus interacting with the cognate synthetase were determined by footprinting. Backbone bond protection against cleavage by iodine of the phospho-rothioate-containing transcripts was found in the anticodon stem-loop, the D stem-loop and the acceptor stem and weak protection was also seen in the variable loop. Most of the protected phosphates correspond to regions around known identity elements of tRNA(Phe). Enhancement of cleavage at certain positions indicates bending of tRNA(Phe) upon binding to the enzyme. When applied to the three-dimensional model of tRNA(Phe) from yeast the majority of the protections occur on the D loop side of the molecule, revealing that phenylalanyl-tRNA synthetase has a rather complex and novel pattern of interaction with tRNA(Phe), differing from that of other known class II aminoacyl-tRNA synthetases.