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Fast-growing, non-infectious and intracellularly surviving drug resistant Mycobacterium aurum: a model for high-throughput antituberculosis drug screening

Gupta, Antima and Bhakta, Sanjib and Kundu, S. and Gupta, M. and Srivastava, B.S. and Srivastava, R. (2009) Fast-growing, non-infectious and intracellularly surviving drug resistant Mycobacterium aurum: a model for high-throughput antituberculosis drug screening. Journal of Antimicrobial Chemotherapy 64 (4), pp. 774-781. ISSN 0305-7453.

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Official URL: http://dx.doi.org/10.1093/jac/dkp279

Abstract

Objectives: Enoyl acyl-carrier-protein reductase (InhA), the primary endogenous target for isoniazid and ethionamide, is crucial to type-II fatty acid biosynthesis (FAS-II). The objectives of this study were first to generate InhA mutants of Mycobacterium aurum, secondly to characterize InhA-mediated isoniazid and ethionamide resistance mechanisms across those mutants and finally to investigate the interaction of InhA with enzymes in the FAS-II pathway in M. aurum. Methods: Spontaneous mutants were generated by isoniazid overdose and limited broth dilution, while for genetically modified mutants sense–antisense DNA technology was used. Southern hybridization and immunoprecipitation were both used to identify the InhA homologue in M. aurum. The latter method was further used to compare the level of InhA expression in M. aurum with that in corresponding mutants. Isoniazid/ethionamide susceptibility modulation was examined in vitro and ex vivo using a resazurin assay as well as by cfu counting. In addition, circular dichroism and the bacterial twohybrid system were exploited to investigate the interaction of InhA with other enzymes of the FAS-II pathway. Results: A Mycobacterium tuberculosis InhA homologue was detected in M. aurum. Susceptibility to isoniazid/ethionamide was significantly altered in genetically modified mutants and simultaneously InhA was overexpressed in both spontaneous and genetically modified mutants. InhA interacts with other FAS-II enzymes of M. aurum in vivo. Conclusion: Close resemblance of isoniazid/ethionamide action on InhA between M. tuberculosis and M. aurum further supports the use of fast-growing and intracellularly surviving drug-resistant M. aurum to substitute for highly virulent, extremely slow-growing M. tuberculosis strains in the early stage of antituberculosis inhibitor screening.

Item Type: Article
Keyword(s) / Subject(s): antibacterial drug screening, drug resistance, enoyl acyl-carrier-protein reductase, protein–protein interaction, surrogate
School or Research Centre: Birkbeck Schools and Research Centres > School of Science > Biological Sciences
Depositing User: Dr Antima Gupta
Date Deposited: 30 Nov 2011 11:42
Last Modified: 17 Apr 2013 12:33
URI: http://eprints.bbk.ac.uk/id/eprint/4441

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