A transcription termination signal immediately precedes the coding sequence for the chloramphenicol-inducible plasmid gene cat-86.
The plasmid gene cat-86 specifies chloramphenicol-inducible, chloramphenicol acetyltransferase in Bacillus subtilis. The inducible regulation is independent of the promoter that is used to activate cat-86 and is independent of the cat-86 coding sequence. We have proposed that the regulation of cat-86 results from the transcription of a pair of inverted-repeat sequences that immediately precede the coding sequence. These transcripts are predicted to sequester the cat-86 ribosome binding site in a stable RNA stem-loop which, in theory, should block the ribosome binding site from pairing with 16S rRNA. Inducible expression of cat-86 may therefore result in part from regulation of the translation of cat-86 mRNA. However, chloramphenicol-induction correlates with increased levels of cat-86 mRNA and the RNA stem-loop preceding the cat-86 coding sequence structurally resembles a rho-independent transcription terminator. We have therefore tested the inverted-repeats as a potential site of transcription termination. Transcription studies performed in vitro using SP6 RNA polymerase and in vivo by S1 mapping demonstrate that a substantial fraction of the potential cat-86 transcripts terminate at a site immediately 3' to the inverted-repeats. The results of the in vivo experiments suggest that the termination signal may be partially relieved by growth of cells in chloramphenicol.
D000123:Acetyltransferases / Q000235:genetics*; D001412:Bacillus subtilis / Q000235:genetics*; D001483:Base Sequence; D002701:Chloramphenicol / Q000494:pharmacology*; D015500:Chloramphenicol O-Acetyltransferase; D012321:DNA-Directed RNA Polymerases / Q000235:genetics; D004790:Enzyme Induction; D005786:Gene Expression Regulation / Q000187:drug effects; D005798:Genes, Bacterial; D005809:Genes, Regulator; D009690:Nucleic Acid Conformation; D010957:Plasmids; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic / Q000187:drug effects
D002701:Chloramphenicol; D000123:Acetyltransferases; D015500:Chloramphenicol O-Acetyltransferase; D012321:DNA-Directed RNA Polymerases