title: Expression of Mycobacterium tuberculosis Rv1991c using an arabinose-inducible promoter demonstrates its role as a toxin.
abstract: Conditional gene expression systems are useful tools for studying the role of essential or toxic gene products in bacterial systems. There is a paucity of such systems available for use in the mycobacteria. The utility of the Escherichia coli arabinose-inducible system was looked into, since it is tightly controlled in response to the presence of arabinose and glucose. It was demonstrated that the P(BAD) promoter can be used to express heterologous genes in Mycobacterium smegmatis. Expression of a lacZ reporter gene demonstrated that promoter activity was inducible in response to the presence of glucose, but only on solid medium. This system was utilized to study the functional consequences of expressing one member of a putative toxin-antitoxin pair (Rv1991c). Rv1991c has homology with a number of bacterial toxins, including ChpK, MazF and PemK. A potential antitoxin gene has been identified, adjacent to Rv1991c in the genome, which was coexpressed with the toxin. Expression of the toxin alone inhibited the growth of E. coli, whereas coexpression with the antitoxin did not. Expression of Rv1991c also led to a marked reduction of cell viability in M. smegmatis, confirming its role as a potent toxin.
authors.affiliation: Centre for Infectious Disease, Institute of Cell and Molecular Science, Barts and the London, Queen Mary's School of Medicine and Dentistry, Whitechapel, London, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Carroll
authors.forename: Amanda C
authors.initials: AC
authors.lastname: Brown
authors.forename: Anna R
authors.initials: AR
authors.lastname: Hartridge
authors.forename: Tanya
authors.initials: T
authors.lastname: Parish
mesh_terms: D000595:Amino Acid Sequence; D001089:Arabinose; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D001427:Bacterial Toxins / Q000737:chemistry / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development; D017930:Genes, Reporter; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D011401:Promoter Regions, Genetic; D016415:Sequence Alignment
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D001089:Arabinose