Drug-free induction of a chloramphenicol acetyltransferase gene in Bacillus subtilis by stalling ribosomes in a regulatory leader.
The plasmid gene cat-86 is induced by chloramphenicol in Bacillus subtilis, resulting in the synthesis of the gene product chloramphenicol acetyltransferase. Induction is due to a posttranscriptional regulatory mechanism in which the inducer, chloramphenicol, activates translation of cat-86 mRNA. We have suggested that chloramphenicol allows ribosomes to destabilize a stem-loop structure in cat-86 mRNA that sequesters the ribosome-binding site for the coding sequence. In the present report we show that cat-86 expression can be activated by stalling ribosomes in the act of translating a regulatory leader peptide. Stalling was brought about by starving host cells for specific leader amino acids. Ribosomal stalling, which led to cat-86 expression, occurred upon starvation for the amino acid specified by the leader codon located immediately 5' to the RNA stem-loop structure and was independent of whether that codon specified lysine or tyrosine. These observations support a model for chloramphenicol induction of cat-86 in which the antibiotic stalls ribosome transit in the regulatory leader. Stalling of ribosomes in the leader can therefore lead to destabilization of the RNA stem-loop structure.
D000123:Acetyltransferases / Q000096:biosynthesis / Q000235:genetics*; D001412:Bacillus subtilis / Q000201:enzymology / Q000235:genetics*; D002701:Chloramphenicol / Q000494:pharmacology; D015500:Chloramphenicol O-Acetyltransferase; D003062:Codon; D003470:Culture Media; D004790:Enzyme Induction; D005786:Gene Expression Regulation; D005798:Genes, Bacterial; D008239:Lysine / Q000235:genetics / Q000494:pharmacology; D008957:Models, Genetic; D014176:Protein Biosynthesis; D021382:Protein Sorting Signals / Q000235:genetics; D011741:Pyrimidine Nucleosides / Q000494:pharmacology; D012270:Ribosomes / Q000378:metabolism*
D003062:Codon; D003470:Culture Media; D021382:Protein Sorting Signals; D011741:Pyrimidine Nucleosides; C004413:amicetin; D002701:Chloramphenicol; D000123:Acetyltransferases; D015500:Chloramphenicol O-Acetyltransferase; D008239:Lysine