Recessive nonsense-suppression in yeast Saccharomyces cerevisiae: the study of 80 S ribosomes accumulated in suppressor strain under non-permissive conditions.
The shift of recessive suppressor mutant of yeast Saccharomyces cerevisiae from permissive to restrictive conditions is accompanied by polysome decay and accumulation of 80 S ribosomes (Smirnov et al., 1976). In this paper some properties of 80 S ribosomes are studied. It is demonstrated that polysome decay under non-permissive conditions is not the consequence of the impairment of RNA synthesis. More than 70% of 80 S ribosomes accumulated under non-permissive conditions contain bound peptidyl-tRNAs localized in P-ribosomal site. tRNA moiety of bound peptidyl-tRNA is able to accept all 20 natural amino acids after chemical deacylation. Therefore it is not a specific isoacceptor species but rather total tRNA that is bound to ribosomes. The polypeptide residues of these peptidyl-tRNAs are heterogeneous in size. Their molecular weights are comparable with the molecular weights of the completed polypeptides. Some of the 80 S ribosomes accumulated under non-permissive conditions contain poly-A+ RNA. In conclusion, possible mechanism of the impairment of translation under non-permissive conditions in recessive suppressor strain is discussed.
D005808:Genes, Recessive; D008970:Molecular Weight; D014176:Protein Biosynthesis; D012343:RNA, Transfer / Q000378:metabolism; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D013489:Suppression, Genetic
D012346:RNA, Transfer, Amino Acyl; D012343:RNA, Transfer