An attenuated mutant of the Rv1747 ATP-binding cassette transporter ofMycobacterium tuberculosisand a mutant of its cognate kinase, PknF, show increased expression of the efflux pump-relatediniBACoperon

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.

Cmr is a redox-responsive regulator of DosR that contributes to M. tuberculosis virulence

“…RNA isolation from M. tuberculosis liquid cultures was described previously (17). Whole genome DNA microarrays of M. tuberculosis (version 2) were provided by the BμG@S group (St. George's, University of London).…”

The thick waxy coat of mycobacteria, a protective layer against antibiotics and the host's immune system

“…A candidate for this transport is the putative ABC transporter, Rv1747, a knock-out of which had low levels of PIMs and showed reduced virulence [198]. However, this mutant still had WT levels of LM and LAM, suggesting the presence of an additional transport mechanism [199]. In the periplasm, membrane-bound GTs transfer further mannose units from the lipid-linked donor, polyprenyl-mannose [182].…”

Chemical Genetic Interaction Profiling Reveals Determinants of Intrinsic Antibiotic Resistance in Mycobacterium tuberculosis

“…3). Mutant frequencies for rv1747, encoding a probable ATP-binding protein ABC transporter, were significantly reduced after outgrowth with vancomycin, whereas transposon insertions disrupting rv1410c, encoding an efflux pump (34), were underrepresented after selection with vancomycin, rifampin, and meropenem; however, both genes have also been implicated in cell wall biosynthesis (35,36) and may thus contribute to drug resistance in a drug effluxindependent manner.…”