title: Translational polarity of a mutation in the initiator AUG codon of the lambda cI gene.
abstract: A PRM-cI-lacZ fusion inserted into the b2 region of bacteriophage lambda was used to isolate mutations affecting expression of both the lambda cI gene and the lacZ gene. One such mutation, a change in the cI initiator codon from AUG to AUA, reduces immunity of a lambda prophage to superinfection, and causes a 60-70% reduction in beta-galactosidase synthesis, even when repressor is supplied in trans. The effect of the mutation on lacZ gene expression is eliminated in a rho- bacterial strain, and the mutation has no effect on transcription initiated at PRM in vitro. Therefore, the effects of the mutation are due to premature p-dependent termination of transcription in the absence of translation of the cI gene, as if the mutation were a nonsense polar mutation.
mesh_terms: D010582:Bacteriophage lambda / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D003062:Codon; D004926:Escherichia coli / Q000235:genetics*; D005696:Galactosidases / Q000235:genetics*; D005814:Genes, Viral; D008969:Molecular Sequence Data; D009154:Mutation; D014176:Protein Biosynthesis; D012333:RNA, Messenger; D012097:Repressor Proteins / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic; D001616:beta-Galactosidase / Q000235:genetics*
chemical_list: D003062:Codon; D012333:RNA, Messenger; D012097:Repressor Proteins; D014157:Transcription Factors; D005696:Galactosidases; D001616:beta-Galactosidase