Open AccessAmino acids are not all initially attached to the same position on transfer RNA molecules.
Author(s) -
Thomas H. Fraser,
Alexander Rich
Publication year - 1975
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.72.8.3044
Subject(s) - amino acid , transfer rna , aminoacylation , biochemistry , alanine , valine , amino acyl trna synthetases , peptide bond , phenylalanine , chemistry , asparagine , leucine , methionine , amino acid synthesis , stereochemistry , aspartic acid , serine , threonine , lysine , enzyme , rna , gene
Escherichia coli tRNA has been modified by replacement of the 3'-terminal AMP with either 3'-amino-3'-deoxy AMP of 2'-amino-2'-deoxy AMP. These tRNA analogs have enabled us to determine the initial site of enzyme-catalyzed aminoacylation of different tRNAs by the formation of aminoacyl-tRNA molecules in which the amino acid is linked to the 3'-terminal ribose through a stable amide bond. The tRNA species specific for glutamic acid, glutamine, leucine, phenylalanine, tyrosine, and valine are all aminoacylated on the 2'-hydroxyl group. The tRNA species specific for alanine, asparagine, aspartic acid, glycine, histidine, lysine, and threonine are aminoacylated on the 3'-hydroxyl group. The amino acids arginine, isoleucine, methionine, proline, serine, and tryptophan form stable amide bonds with both amino tRNA analogs. This might suggest that the synthetases for these amino acids can acylate both the 2'- and 3'-hydroxyl groups, but it is more likely that these enzymes can acylate both hydroxyl and amino groups at either the 2' or 3'-position of the tRNA. These results clearly illustrate a fundamental heterogeneity which is apparent in the mechanism of action of aminoacyl-tRNA synthetases.