title: The mycobacterial transcriptional regulator whiB7 gene links redox homeostasis and intrinsic antibiotic resistance.
abstract: Intrinsic drug resistance in Mycobacterium tuberculosis limits therapeutic options for treating tuberculosis. The mycobacterial transcriptional regulator whiB7 contributes to intrinsic resistance by activating its own expression and many drug resistance genes in response to antibiotics. To investigate whiB7 activation, we constructed a GFP reporter to monitor its expression, and we used it to investigate the whiB7 promoter and to screen our custom library of almost 600 bioactive compounds, including the majority of clinical antibiotics. Results showed whiB7 was transcribed from a promoter that was conserved across mycobacteria and other actinomycetes, including an AT-rich sequence that was likely targeted by WhiB7. Expression was induced by compounds having diverse structures and targets, independent of the ability of whiB7 to mediate resistance, and was dependent on media composition. Pretreatment with whiB7 activators resulted in clinically relevant increases in intrinsic drug resistance. Antibiotic-induced transcription was synergistically increased by the reductant dithiothreitol, an effect mirrored by a whiB7-dependent shift to a highly reduced cytoplasm reflected by the ratio of reduced/oxidized mycothiol. These data provided evidence that intrinsic resistance resulting from whiB7 activation is linked to fundamental changes in cell metabolism.
authors: Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada; Centre for Tuberculosis Research, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada.
authors: Ján
authors: J
authors: Burian
authors: Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada; Centre for Tuberculosis Research, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada.
authors: Santiago
authors: S
authors: Ramón-García
authors: Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada; Centre for Tuberculosis Research, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada.
authors: Gaye
authors: G
authors: Sweet
authors: Centre for Tuberculosis Research, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada; Department of Medicine, Division of Infectious Diseases, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.
authors: Anaximandro
authors: A
authors: Gómez-Velasco
authors: Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada; Centre for Tuberculosis Research, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada; Department of Medicine, Division of Infectious Diseases, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.
authors: Yossef
authors: Y
authors: Av-Gay
authors: Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada; Centre for Tuberculosis Research, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada. Electronic address: charles.thompson@ubc.ca.
authors: Charles J
authors: CJ
authors: Thompson
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D024881:Drug Resistance, Bacterial / Q000187:drug effects / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects / Q000235:genetics; D017930:Genes, Reporter / Q000235:genetics; D006706:Homeostasis / Q000187:drug effects* / Q000235:genetics*; D008969:Molecular Sequence Data; D009161:Mycobacterium / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D059372:Nucleotide Motifs / Q000235:genetics; D010084:Oxidation-Reduction / Q000187:drug effects; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins