title: Expression of the Escherichia coli chromosomal ars operon.
abstract: A chromosomally located operon (ars) of Escherichia coli has been previously shown to be functional in arsenic detoxification. DNA sequencing revealed three open reading frames homologous to the arsR, arsB, and arsC open reading frames of plasmid-based arsenic resistance operons isolated from both E. coli and staphylococcal species. To examine the outline of transcriptional regulation of the chromosomal ars operon, several transcriptional fusions, using the luciferase-encoding luxAB genes of Vibrio harveyi, were constructed. Measurement of the expression of these gene fusions demonstrated that the operon was rapidly induced by sodium arsenite and negatively regulated by the trans-acting arsR gene product. Northern blotting and primer extension analyses revealed that the chromosomal ars operon is most likely transcribed as a single mRNA of approximately 2100 nucleotides in length and processed into two smaller mRNA products in a manner similar to that found in the E. coli R773 plasmid-borne ars operon. However, transcription was found to initiate at a position that is relatively further upstream of the initiation codon of the arsR coding sequence than that determined for the E. coli R773 plasmid's ars operon.
authors.affiliation: Department of Microbiology and Immunology, McGill University, Montréal, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Cai
authors.forename: M S
authors.initials: MS
authors.lastname: DuBow
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics*; D000965:Antimony / Q000494:pharmacology; D001151:Arsenic / Q000494:pharmacology; D053501:Arsenite Transporting ATPases; D001426:Bacterial Proteins; D001483:Base Sequence; D002876:Chromosomes, Bacterial / Q000235:genetics*; D003001:Cloning, Molecular; D017931:DNA Primers; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D016623:Ion Pumps; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes; D009690:Nucleic Acid Conformation; D009876:Operon; D010957:Plasmids; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000302:isolation & purification; D015534:Trans-Activators / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: C489527:ArsR protein, E coli; D001426:Bacterial Proteins; D017931:DNA Primers; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D016623:Ion Pumps; D009097:Multienzyme Complexes; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D000965:Antimony; D008156:Luciferases; D000251:Adenosine Triphosphatases; D053501:Arsenite Transporting ATPases; D001151:Arsenic