Lack of correlation between affinity of the tRNA for the aminoacyl-tRNA synthetase and aminoacylation capacity as studied with modified tRNAPhe.
The interactions of several modified yeast tRNAPhe [tRNAPhe lacking 7-methylguanine; a fragment comprising about 3/4 of the whole molecule: tRNAPhe (18--76); tRNAPhe (18--76) lacking 7-methylguanine] with yeast phenylalanyl-tRNA synthetase were studied. Upon excision of the 5'-quarter of the tRNAPhe molecule, the residual fragment still tightly binds to the synthetase, but can no longer by aminoacylated. Surprisingly, upon removal of the 7-methylguanine base at position 46 in this fragment, althought the affinity drops by a factor 10, a significant aminoacylation is restored. These results are discussed in terms of molecular flexibility and a model is proposed for tRNA-enzyme interaction, involving multisite recognition.
D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism*; D001665:Binding Sites; D007700:Kinetics; D046911:Macromolecular Substances; D010649:Phenylalanine; D010652:Phenylalanine-tRNA Ligase / Q000302:isolation & purification / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D012343:RNA, Transfer; D012441:Saccharomyces cerevisiae / Q000201:enzymology
D046911:Macromolecular Substances; D010649:Phenylalanine; D012343:RNA, Transfer; D000604:Amino Acyl-tRNA Synthetases; D010652:Phenylalanine-tRNA Ligase