title: Nonsense suppression in aminoacyl-t-RNA limited cells.
abstract: A number of nonsense alleles of lacZ exhibit phenotypic suppression (as much as a sixteen-fold increase in leakiness) during partial limitation for certain aminoacyl-tRNA species in relA mutant cells. Each responsive allele has its individual pattern of response to limitation for one or more amino acids or aminoacyl-tRNA's. The phenotypic suppression occurs only during limitation, and ceases once limitation is reversed. Suppression is much reduced by the presence of the relA+ allele or an allele of rpsL which restricts ribosomal ambiguity. In one case, the suppressed product has been identified by radioimmune assay and gel electrophoresis, and is a full-length lacZ protomer. Mechanisms are discussed whereby aberrations of translation at codons calling for an aminoacyl-tRNA species in short supply might lead to readthrough of a nearby nonsense codon.
mesh_terms: D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D005786:Gene Expression Regulation; D007763:Lac Operon; D009694:Nucleic Acid Precursors / Q000235:genetics; D014176:Protein Biosynthesis; D012329:RNA, Bacterial / Q000235:genetics; D012343:RNA, Transfer / Q000235:genetics; D012346:RNA, Transfer, Amino Acyl / Q000235:genetics*; D000091243:Ribosomal Protein S9; D013489:Suppression, Genetic
chemical_list: D029968:Escherichia coli Proteins; D009694:Nucleic Acid Precursors; D012329:RNA, Bacterial; D012346:RNA, Transfer, Amino Acyl; D000091243:Ribosomal Protein S9; C000717190:RpsI protein, E coli; D012343:RNA, Transfer