1993 Volume 5 Issue 2 Pages 39-42
It has been known that transfer RNA assumes a functional conformation in the presence of certain metal ions, most commonly magnesium ions. Several Mg2+-binding sites of high affinity have been revealed by X-ray crystallographic analyses of yeast tRNAPhe. On the other hand, ATP, a naturally occurring high-energy compound and which is one of the substrates in aminoacylation of tRNA, is known to have ability to chelate Mg2+. We therefore examined the possibility that the conformation of tRNA is regulated by the quantitative balance between Mg2+ and ATP, and consequently biological activity of tRNA is modulated as well. Structural transition of tRNA was monitored by measuring the melting profiles of yeast tRNATyr in the presence of Mg2+ and/or ATP at various [ATP]/[Mg2+] ratios. Tyrosine-accepting activity of yeast tRNATyr was also measured under the similar solution conditions. These results clearly indicated that conformation of tRNA and its aminoacylation capacity can be easily modulated by changing the relative concentration ratio of Mg2+ and ATP.