Effect of Threonylcarbamoyl Modification (t6A) in Yeast tRNAArgIII on Codon‐Anticodon and Anticodon‐Anticodon Interactions: A Thermodynamic and Kinetic Evaluation

摘要

The effect of N‐[9‐(β‐d‐ribofuranosyl) purin‐6‐ylcarbamoyl]threonine (t6A) adjacent to anticodon U*‐C‐U of yeast tRNAArgIII (where U* is a modified U), compared to its unmodified adenosine counterpart, has been evaluated by three independent methods: (a) the polynucleotide‐directed binding of tRNA on ribosomes, (b) the ribosome‐free trinucleotide binding to the anticodon. (c) the anticodon‐anticodon binding test. The results obtained by these three methods indicate a small but significant stabilization effect of t6A on the binding of yeast tRNAArgIII with (a) poly(A,G) in the presence of Escherichia coli ribosomes, (b) free A‐G‐A triplet, and (c) E.coli tRNAServ (anticodon G‐G‐A). We therefore conclude that the stabilization effect of t6A occurs on U · A and U · G base pairs adjacent to the 5′ side of the modified nucleoside, most probably by stacking. Copyright © 1981, Wiley Blackwell. All rights reserved