title: Unique Regulation of the DosR Regulon in the Beijing Lineage of Mycobacterium tuberculosis.
abstract: The DosR regulon, a set of 48 genes normally expressed in Mycobacterium tuberculosis under conditions that inhibit aerobic respiration, is controlled via the DosR-DosS/DosT two-component system. While the regulon requires induction in most M. tuberculosis isolates, for members of the Beijing lineage, its expression is uncoupled from the need for signaling. In our attempts to understand the mechanistic basis for this uncoupling in the Beijing background, we previously reported the identification of two synonymous single-nucleotide polymorphisms (SNPs) within the adjacent Rv3134c gene. In the present study, we have interrogated the impact of these SNPs on dosR expression in wild-type strains, as well as a range of dosR-dosS-dosT mutants, for both Beijing and non-Beijing M. tuberculosis backgrounds. In this manner, we have unequivocally determined that the C601T dosR promoter SNP is the sole requirement for the dramatic shift in the pattern of DosR regulon expression seen in this globally important lineage. Interestingly, we also show that DosT is completely nonfunctional within these strains. Thus, a complex series of evolutionary steps has led to the present-day Beijing DosR phenotype that, in turn, potentially confers a fitness advantage in the face of some form of host-associated selective pressure.
  
  
  
  Mycobacterium tuberculosis strains of the Beijing lineage have been described as being of enhanced virulence compared to other lineages, and in certain regions, they are associated with the dramatic spread of multidrug-resistant tuberculosis (TB). In terms of trying to understand the functional basis for these broad epidemiological phenomena, it is interesting that, in contrast to the other major lineages, the Beijing strains all constitutively overexpress members of the DosR regulon. Here, we identify the mutational events that led to the evolution of this unique phenotype. In addition, our work highlights the fact that important phenotypic differences exist between distinct M. tuberculosis lineages, with the potential to impact the efficacy of diagnosis, vaccination, and treatment programs.
authors: Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada.|Department of Medicine, McGill University, Montreal, Quebec, Canada.
authors: Pilar
authors: P
authors: Domenech
authors: Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada.|Department of Microbiology & Immunology, McGill University, Montreal, Quebec, Canada.
authors: Jason
authors: J
authors: Zou
authors: Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada.|Department of Microbiology & Immunology, McGill University, Montreal, Quebec, Canada.
authors: Alexandra
authors: A
authors: Averback
authors: Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada.|Department of Microbiology & Immunology, McGill University, Montreal, Quebec, Canada.
authors: Nishath
authors: N
authors: Syed
authors: Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada.|Department of Microbiology & Immunology, McGill University, Montreal, Quebec, Canada.
authors: Daniele
authors: D
authors: Curtis
authors: Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada.|Department of Microbiology & Immunology, McGill University, Montreal, Quebec, Canada.
authors: Samuel
authors: S
authors: Donato
authors: Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada michael.reed@mcgill.ca.|Department of Medicine, McGill University, Montreal, Quebec, Canada.|McGill International TB Centre, Montreal, Quebec, Canada.
authors: Michael B
authors: MB
authors: Reed
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D000068476:Beijing; D004268:DNA-Binding Proteins; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D008168:Lung / Q000382:microbiology; D051379:Mice; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000378:metabolism*; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D018085:Regulon / Q000235:genetics / Q000502:physiology*; D016019:Survival Analysis; D014376:Tuberculosis / Q000382:microbiology*
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C542863:DosR protein, Mycobacterium tuberculosis; D011494:Protein Kinases; C542862:DosT protein, Mycobacterium tuberculosis
keywords: DosR regulon; Mycobacterium tuberculosis; Tuberculosis; evolution; strain variation