Open AccessAn attenuated mutant of the R v1747 ATP‐binding cassette transporter of M ycobacterium tuberculosis and a mutant of its cognate kinase, P kn F , show increased expression of the efflux pump‐related ini BAC operon
Author(s) -
Spivey Vicky L.,
Whalan Rachael H.,
Hirst Elizabeth M. A.,
Smerdon Stephen J.,
Buxton Roger S.
Publication year - 2013
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/1574-6968.12230
Subject(s) - operon , biology , ethambutol , atp binding cassette transporter , mutant , transcription (linguistics) , biochemistry , microbiology and biotechnology , gene , transporter , rifampicin , linguistics , philosophy , antibiotics
The ATP ‐binding cassette transporter R v1747 is required for the growth of M ycobacterium tuberculosis in mice and in macrophages. Its structure suggests it is an exporter. R v1747 forms a two‐gene operon with pknF coding for the serine/threonine protein kinase P kn F , which positively modulates the function of the transporter. We show that deletion of R v1747 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 R v1747 or pkn F 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 R v1747 affects cell wall biosynthesis leading to the production of intermediates that cause induction of ini BAC transcription and implicates it in exporting a component of the cell wall, which is necessary for virulence.