ermC leader peptide. Amino acid sequence critical for induction by translational attenuation.
The ermC mRNA leader segment, which encodes a 19 amino acid leader peptide, MGIFSIFVISTVHYQPNKK, plays a key role in regulating expression of the ErmC methylase. The contribution of specific leader peptide amino acid residues to induction of ermC was studied using a model system in which the ErmC methylase was translationally fused to Escherichia coli beta-galactosidase as indicator gene. Codons of the ermC leader peptide were altered systematically by replacement of leader DNA segments with double-stranded DNA constructed from chemically synthesized oligonucleotides. Missense mutations that resulted in reduced efficiency of induction involved codons for amino acid residues 5 to 9 (-SIFVI-). Nonsense mutations causing termination of the leader peptide at codons 10 (-S-) or 12 (-V-) remained inducible. These findings suggest that the codons for residues 5 to 9 of the leader peptide comprise the critical region in which ribosomes stall in the presence of erythromycin.
Mayford
M
M
Department of Molecular Biology, University of Wisconsin, Madison 53706.
Weisblum
B
B
D000595:Amino Acid Sequence; D003062:Codon; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli; D005786:Gene Expression Regulation; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009154:Mutation; D014176:Protein Biosynthesis; D021382:Protein Sorting Signals / Q000235:genetics*; D012329:RNA, Bacterial / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics*
D003062:Codon; D004269:DNA, Bacterial; D021382:Protein Sorting Signals; D012329:RNA, Bacterial; D012333:RNA, Messenger