Role of VapBC12 toxin-antitoxin locus in cholesterol-induced mycobacterial persistence

Sakshi Talwar, Manitosh Pandey, Chandresh Sharma, Rintu Kutum, Josephine Lum, Daniel Carbajo, Renu Goel, Michael Poidinger, Debasis Dash, Amit Singhal, Amit Kumar Pandey*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


The worldwide increase in the frequency of multidrug-resistant and extensively drug-resistant cases of tuberculosis is mainly due to therapeutic noncompliance associated with a lengthy treatment regimen. Depending on the drug susceptibility profile, the treatment duration can extend from 6 months to 2 years. This protracted regimen is attributed to a supposedly nonreplicating and metabolically inert subset of the Mycobacterium tuberculosis population, called "persisters."The mechanism underlying stochastic generation and enrichment of persisters is not fully known. We have previously reported that the utilization of host cholesterol is essential for mycobacterial persistence. In this study, we have demonstrated that cholesterol- induced activation of a RNase toxin (VapC12) inhibits translation by targeting proT tRNA in M. tuberculosis. This results in cholesterol-specific growth modulation that increases the frequency of generation of the persisters in a heterogeneous M. tuberculosis population. Also, a null mutant strain of this toxin (DvapC12) demonstrated an enhanced growth phenotype in a guinea pig model of M. tuberculosis infection, depicting its role in disease persistence. Thus, we have identified a novel strategy through which cholesterol-specific activation of a toxin-antitoxin module in M. tuberculosis enhances persister formation during infection. The current findings provide an opportunity to target persisters, a new paradigm facilitating tuberculosis drug development. IMPORTANCE The current TB treatment regimen involves a combination of drugs administered for an extended duration that could last for 6months to 2 years. This could lead to noncompliance and the emergence of newer drug resistance strains. It is widely perceived that the major culprits are the so-called nonreplicating and metabolically inactive "persister"bacteria. The importance of cholesterol utilization during the persistence stage of M. tuberculosis infection and its potential role in the generation of persisters is very intriguing. We explored the mechanism involved in the cholesterol-mediated generation of persisters in mycobacteria. In this study, we have identified a toxin-antitoxin (TA) system essential for the generation of persisters during M. tuberculosis infection. This study verified that M. tuberculosis strain devoid of the VapBC12 TA system failed to persist and showed a hypervirulent phenotype in a guinea pig infection model. Our studies indicate that the M. tuberculosis VapBC12 TA system acts as a molecular switch regulating persister generation during infection. VapBC12 TA system as a drug target offers opportunities to develop shorter and more effective treatment regimens against tuberculosis.

Original languageEnglish (US)
Article numbere00855-20
Issue number6
StatePublished - Dec 15 2020


  • Cholesterol
  • Host-pathogen interactions
  • Mycobacteria
  • Toxin-antitoxin

ASJC Scopus subject areas

  • Microbiology
  • Physiology
  • Biochemistry
  • Ecology, Evolution, Behavior and Systematics
  • Modeling and Simulation
  • Molecular Biology
  • Genetics
  • Computer Science Applications


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