title: Mutation of Rv2887, a marR-like gene, confers Mycobacterium tuberculosis resistance to an imidazopyridine-based agent.
abstract: Drug resistance is a major problem in Mycobacterium tuberculosis control, and it is critical to identify novel drug targets and new antimycobacterial compounds. We have previously identified an imidazo[1,2-a]pyridine-4-carbonitrile-based agent, MP-III-71, with strong activity against M. tuberculosis. In this study, we evaluated mechanisms of resistance to MP-III-71. We derived three independent M. tuberculosis mutants resistant to MP-III-71 and conducted whole-genome sequencing of these mutants. Loss-of-function mutations in Rv2887 were common to all three MP-III-71-resistant mutants, and we confirmed the role of Rv2887 as a gene required for MP-III-71 susceptibility using complementation. The Rv2887 protein was previously unannotated, but domain and homology analyses suggested it to be a transcriptional regulator in the MarR (multiple antibiotic resistance repressor) family, a group of proteins first identified in Escherichia coli to negatively regulate efflux pumps and other mechanisms of multidrug resistance. We found that two efflux pump inhibitors, verapamil and chlorpromazine, potentiate the action of MP-III-71 and that mutation of Rv2887 abrogates their activity. We also used transcriptome sequencing (RNA-seq) to identify genes which are differentially expressed in the presence and absence of a functional Rv2887 protein. We found that genes involved in benzoquinone and menaquinone biosynthesis were repressed by functional Rv2887. Thus, inactivating mutations of Rv2887, encoding a putative MarR-like transcriptional regulator, confer resistance to MP-III-71, an effective antimycobacterial compound that shows no cross-resistance to existing antituberculosis drugs. The mechanism of resistance of M. tuberculosis Rv2887 mutants may involve efflux pump upregulation and also drug methylation.
authors: Center for Tuberculosis Research, Department of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.
authors: Kathryn
authors: K
authors: Winglee
authors: Center for Tuberculosis Research, Department of Medicine, Johns Hopkins University, Baltimore, Maryland, USA.
authors: Shichun
authors: S
authors: Lun
authors: Dipartimento di Farmacia, P4T group, University of Parma, Parma, Italy.
authors: Marco
authors: M
authors: Pieroni
authors: Drug Discovery Program, Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, Chicago, Illinois, USA.
authors: Alan
authors: A
authors: Kozikowski
authors: Center for Tuberculosis Research, Department of Medicine, Johns Hopkins University, Baltimore, Maryland, USA wbishai1@jhmi.edu.
authors: William
authors: W
authors: Bishai
mesh_terms: D000995:Antitubercular Agents / Q000737:chemistry* / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D024901:Drug Resistance, Multiple, Bacterial; D007538:Isoniazid / Q000737:chemistry*; D008826:Microbial Sensitivity Tests; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics*
chemical_list: D000995:Antitubercular Agents; D001426:Bacterial Proteins; D007538:Isoniazid