Pleiotrophic effects of point mutations in yeast tRNA(Asp) on the base modification pattern.

The base-modification pattern has been studied in several synthetic variants of yeast tRNA(Asp) injected into Xenopus laevis oocytes. Certain point mutations in the D-stem and the variable loop of the tRNA led to considerably decreased levels of m1G37, psi 40 and Q34/manQ34 in the anticodon stem or loop and an increased rate of synthesis for m5C49 in the T-stem. The formation of m2G6 in the aminoacyl-stem was not affected in any of the tRNA-variants. Thus, mutations in one part of the tRNA-molecule can have long-range effects on the interactions between another part of the tRNA and the tRNA modifying enzymes.