Mycobacterium tuberculosis Proteome Response to Antituberculosis Compounds Reveals Metabolic “Escape” Pathways That Prolong Bacterial Survival

Abstract

Tuberculosis (TB) continues to be one of the most common bacterial infectious diseases and is the leading cause of death in many parts of the world. A major limitation of TB therapy is slow killing of the infecting organism, increasing the risk for the development of a tolerance phenotype and drug resistance. Studies indicate that <i>Mycobacterium tuberculosis</i> takes several days to be killed upon treatment with lethal concentrations of antibiotics both <i>in vitro</i> and <i>in vivo</i> To investigate how metabolic remodeling can enable transient bacterial survival during exposure to bactericidal concentrations of compounds, <i>M. tuberculosis</i> strain H37Rv was exposed to twice the MIC of isoniazid, rifampin, moxifloxacin, mefloquine, or bedaquiline for 24 h, 48 h, 4 days, and 6 days, and the bacterial proteomic response was analyzed using quantitative shotgun mass spectrometry. Numerous sets of <i>de novo</i> bacterial proteins were identified over the 6-day treatment. Network analysis and comparisons between the drug treatment groups revealed several shared sets of predominant proteins and enzymes simultaneously belonging to a number of diverse pathways. Overexpression of some of these proteins in the nonpathogenic <i>Mycobacterium smegmatis</i> extended bacterial survival upon exposure to bactericidal concentrations of antimicrobials, and inactivation of some proteins in <i>M. tuberculosis</i> prevented the pathogen from escaping the fast killing <i>in vitro</i> and in macrophages, as well. Our biology-driven approach identified promising bacterial metabolic pathways and enzymes that might be targeted by novel drugs to reduce the length of tuberculosis therapy.