Biopolymers and cell. 1992; 8 (2): 37 - 43

SHUL'GA N. I.

The Effect of Mg2+ and tRNA on Synthetic Templates Translation Ambiquity in Cell-Free Systems From Different Saccharomyces cerevisiae Strains

Summary

    Cell-free systems (S-30) have been obtained an characterized from yeast straines differing in translation accuracy in vivo. Investigation of leucine misincorpora-iion into poly(U) translation product has shown that S-30 systems from parent strains (12V-P4280 and 125A-P2156) have higher accuracy index Leu / Phe in comparison with S-30 systems from supressor strains (3-12V-P4280 and 4-125A-P2156) carrying muta¬tion in sup-1 (sup-45) gene. Analysis of the basis of these differences has demonstrated that they can be caused by tRNAs aminoacylation level and accordingly by alteration of individual aminoacyl-tRNAs ratio in systems from different origins. This factor can be overcame by exogenouse yeast tRNA addition. High Mg2+ ions concentration as well as tRNA deficit in the samples have been assumed to cause poly(U) translation ambiquity increase. Mg2+ stimulation of poly(dT) translation has been revealed under tRNA deficit. Saturating of the system with tRNA leades to the marked decrease of this translation.