title: An attenuated mutant of the Rv1747 ATP-binding cassette transporter of Mycobacterium tuberculosis and a mutant of its cognate kinase, PknF, show increased expression of the efflux pump-related iniBAC operon.
abstract: The ATP-binding cassette transporter Rv1747 is required for the growth of Mycobacterium tuberculosis in mice and in macrophages. Its structure suggests it is an exporter. Rv1747 forms a two-gene operon with pknF coding for the serine/threonine protein kinase PknF, which positively modulates the function of the transporter. We show that deletion of Rv1747 or pknF results in a number of transcriptional changes which could be complemented by the wild type allele, most significantly up-regulation of the iniBAC genes. This operon is inducible by isoniazid and ethambutol and by a broad range of inhibitors of cell wall biosynthesis and is required for efflux pump functioning. However, neither the Rv1747 or pknF mutant showed increased susceptibility to a range of drugs and cell wall stress reagents including isoniazid and ethambutol, cell wall structure and cell division appear normal by electron microscopy, and no differences in lipoarabinomannan were found. Transcription from the pknF promoter was not induced by a range of stress reagents. We conclude that the loss of Rv1747 affects cell wall biosynthesis leading to the production of intermediates that cause induction of iniBAC transcription and implicates it in exporting a component of the cell wall, which is necessary for virulence.
authors.affiliation: Division of Mycobacterial Research, MRC National Institute for Medical Research, London, UK.
authors.forename: Vicky L
authors.initials: VL
authors.lastname: Spivey
authors.forename: Rachael H
authors.initials: RH
authors.lastname: Whalan
authors.forename: Elizabeth M A
authors.initials: EM
authors.lastname: Hirst
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Smerdon
authors.forename: Roger S
authors.initials: RS
authors.lastname: Buxton
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics*; D002473:Cell Wall / Q000187:drug effects / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics*; D046228:Microarray Analysis; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics*; D009876:Operon / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*
chemical_list: D018528:ATP-Binding Cassette Transporters; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C487813:Rv1747 protein, Mycobacterium tuberculosis; C487814:PknF protein, Mycobacterium tuberculosis; D017346:Protein Serine-Threonine Kinases
keywords: DNA microarray; isoniazid; mycobacteria; serine/threonine protein kinase; transcriptomics; virulence
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