The effect of paromomycin on the expression of ribosomal suppressors in yeast.

Mutants of the yeast Saccharomyces cerevisiae carrying ribosomal suppressor mutations in either sup1 or sup2 genes express a higher sensitivity to paromomycin - aminoglycoside antibiotic known to induce translational errors in eukaryotes. Paromomycin also induces a phenotypic suppression of all three types of nonsense mutations (ochre, amber and opal), missense mutations and frame-shift mutations. The influence of paromomycin on the activity of ribosomal suppressors has at least two aspects: (1) the drug increases translational ambiguity in sup1 and sup2 mutants in vitro and (2) it induces the alteration (extension or restriction) of sup 1 or sup2 suppression spectra in vivo. A modification of selectivity of the mutant ribosomes towards different tRNAs in the presence of paromomycin is proposed.