Normal yeast tRNA(CAGGln) can suppress amber codons and is encoded by an essential gene.
We have isolated a gene that can encode yeast tRNA(CAGGln). When present on a multicopy plasmid, this gene suppresses the phenotype of a number of amber mutants, but has no effect on the ocher mutants tested. We therefore conclude that the anticodon CUG in tRNA(CAGGln) can decode the amber codon UAG by G-U mispairing, possibly by wobble base-pairing in the first codon position. This represents the second example we have observed in this laboratory of nonsense suppression in yeast by natural tRNA(Gln), involving G-U mispairing in the first codon position. Replacing the genomic copy of the cloned gene with a disrupted tRNA gene results in recessive lethality in heterozygous diploids and is lethal to haploid cells. This lethality can be rescued by transformation of cells with a single copy plasmid containing the tRNA(CAGGln) gene. Thus, the gene encoding tRNA(CAGGln) is apparently essential for viability in yeast, suggesting that it is normally present as a single copy gene.
Weiss
W A
WA
Friedberg
E C
EC
D000818:Animals; D001483:Base Sequence; D003062:Codon; D004271:DNA, Fungal; D005800:Genes, Fungal; D006801:Humans; D009690:Nucleic Acid Conformation; D010957:Plasmids; D012331:RNA, Fungal / Q000235:genetics*; D012333:RNA, Messenger; D012346:RNA, Transfer, Amino Acyl / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D013489:Suppression, Genetic; D013768:Tetrahymena
D003062:Codon; D004271:DNA, Fungal; D012331:RNA, Fungal; D012333:RNA, Messenger; D012346:RNA, Transfer, Amino Acyl