Preprint Article Version 2 Preserved in Portico This version is not peer-reviewed

Overexpression of a Membrane Transport System MSMEG_1381 and MSMEG_1382 Confers Multidrug Resistance in Mycobacterium smegmatis

Version 1 : Received: 30 March 2022 / Approved: 1 April 2022 / Online: 1 April 2022 (07:22:46 CEST)
Version 2 : Received: 23 May 2022 / Approved: 24 May 2022 / Online: 24 May 2022 (11:32:52 CEST)

How to cite: S., S.; Muralikrishnan, B.; Bhat, S.; Ghate, S.; Rao, S.P.; Ajay Kumar, R.; Kurthkoti, K. Overexpression of a Membrane Transport System MSMEG_1381 and MSMEG_1382 Confers Multidrug Resistance in Mycobacterium smegmatis. Preprints 2022, 2022040003 (doi: 10.20944/preprints202204.0003.v2). S., S.; Muralikrishnan, B.; Bhat, S.; Ghate, S.; Rao, S.P.; Ajay Kumar, R.; Kurthkoti, K. Overexpression of a Membrane Transport System MSMEG_1381 and MSMEG_1382 Confers Multidrug Resistance in Mycobacterium smegmatis. Preprints 2022, 2022040003 (doi: 10.20944/preprints202204.0003.v2).

Abstract

Mycobacterium tuberculosis is a leading cause of human mortality worldwide and the emergence of drug-resistantstrains, demands the discovery of new classes of antimycobacterials that can be employed in the therapeutic pipeline. Previously, a secondary metabolite Chrysomycin A, isolated from Streptomyces sp. OA161 was shown to have potent bactericidal activity against drug-resistant clinical isolates of M. tuberculosis and different species of mycobacteria. The antibiotic inhibits the mycobacterial topoisomerase I and DNA gyrase leading to bacterial death, but the mechanisms that could cause resistance are currently unknown. To further understand the resistance mechanism, spontaneous resistance mutants were isolated and subjected to whole-genome sequencing. Mutation in a TetR family transcriptional regulator MSMEG_1380 was identified in the resistant isolates and was close to an operon encoding membrane protein MSMEG_1381 and MSMEG_1382. Sequence analysis and modeling studies indicated that they are components of the Mmp family of efflux pumps and over-expression of either the operon or individual genes conferred resistance to chrysomycin A, isoniazid, and ethambutol that are in TB therapy. Our study highlights the role of membrane transporter proteins in conferring multiple drug resistance and the utility of recombinant strains overexpressing membrane transporters in the drug screening pipeline.

Keywords

Drug resistance; Efflux pump; TetR transcriptional regulator; Mycobacteria; MmpL

Subject

LIFE SCIENCES, Microbiology

Comments (1)

Comment 1
Received: 24 May 2022
Commenter: Krishna Kurthkoti
Commenter's Conflict of Interests: Author
Comment: A new growth curve of the recombinant strains has been included as Fig. 2C. Fig2 and Fig. 5 in the previous versions have been moved to supplementary data. Significant changes to the text in the Results and Discussion sections have been made.
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