Serine substitutions caused by an ochre suppressor in yeast

Genetic analysis of a transposable suppressor gene in Saccharomyces cerevisiae

We have demonstrated in Saccharomyces cerevisiae the transposition of a gene coding for an efficient ochre (UAA) suppressor from a centromere-linked site on chromosome III to two new sites in the yeast genome. One site is on chromosome VI, very close to, if not allelic with, SUP11, one of eight genes coding for a tyrosine-inserting suppressor. The second site is on chromosome III, unlinked to the centromere and distal to the mating type locus. This site is very close to those mapped for the recessive lethal amber suppressors, SUP-RL1 and SUP61.

Super suppressor action spectrum in Neurospora

The action of super suppressors mapping at eight separate loci upon ten different nonsense mutants is examined. These suppressors can be subdivided into seven classes based upon their capacity to restore function to the test mutants.

Suppressor-specificity of antisuppressors in yeast

Eighteen mutations ofSaccharomyces cerevisiae, at eight loci, isolated as antisuppressors ofSUPQ2, an ochre-suppressing allele ofSUP11, were crossed with three other suppressors.

They were found to abolish the ability ofSUP2(inserting tyrosine), to suppress the ochre mutationsade2.1andcan1.100, but not its ability, to suppresshis5.2orlys1.1.When coupled with any antisuppressor,SUPQ5, inserting serine, was also unable to suppressade2.1, but the suppression of other ochre mutations varied from oneasu-SUPQ5strain to another. No antisuppressor affected the ability ofSUP11-am, an amber-suppressing allele ofSUP11, to suppresstrp1.1, an amber mutation.

Killer of Saccharomyces cerevisiae: a double-stranded ribonucleic acid plasmid

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Yeast suppressors of UAA and UAG nonsense codons work efficiently in vitro via tRNA

A cell-free protein-synthesizing system, containing an S-100 fraction from yeast, ribosomal subunits from Krebs ascites cells, and ribosome initiation factors from rabbit reticulocytes, translates yeast, adenovirus, and rabbit globin messenger RNAs and the RNA from bacteriophage Qbeta. An amber mutation in the Qbeta synthetase gene is suppressed in vitro if the S-100 fraction s from yeast strains carrying amber suppressor mutations. Suppressor SUP6-2 gives 16% suppression, and the recessive lethal suppressor RL-1 gives 50% suppression. Extracts from strain FM6, which has the ochre suppressor SUP4-1, give a longer protein product from the normal synthetase gene at Qbeta with an efficiency of 63%. This implies that UAA is the terminator for the synthetase gene, and that synthesis of this read through protein can be used as an assay for ochre suppression. Suppression in each of these cases is mediated by tRNA, since pufified tRNA is the only fraction from suppressing strains that is required in an otherwise nonsuppressing cell-free system.