Pyrazinamide Susceptibility Is Driven by Activation of the SigE-Dependent Cell Envelope Stress Response in Mycobacterium tuberculosis

Joshua Thiede, Nicholas A. Dillon, Michael D Howe, Ranee Aflakpui, Samuel J. Modlin, Sven E. Hoffner, Faramarz Valafar, Yusuke Minato, Anthony D. Baughn

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Pyrazinamide (PZA) plays a crucial role in first-line tuberculosis drug therapy. Unlike other antimicrobial agents, PZA is active against Mycobacterium tuberculosis only at low pH. The basis for this conditional drug susceptibility remains undefined. In this study, we utilized a genome-wide approach to interrogate potentiation of PZA action. We found that mutations in numerous genes involved in central metabolism as well as cell envelope maintenance and stress response are associated with PZA resistance. Further, we demonstrate that constitutive activation of the cell envelope stress response can drive PZA susceptibility independent of environmental pH. Consequently, exposure to peptidoglycan synthesis inhibitors, such as beta-lactams and D-cycloserine, potentiate PZA action through triggering this response. These findings illuminate a regulatory mechanism for conditional PZA susceptibility and reveal new avenues for enhancing potency of this important drug through targeting activation of the cell envelope stress response. IMPORTANCE For decades, pyrazinamide has served as a cornerstone of tuberculosis therapy. Unlike any other antitubercular drug, pyrazinamide requires an acidic environment to exert its action. Despite its importance, the driver of this conditional susceptibility has remained unknown. In this study, a genome-wide approach revealed that pyrazinamide action is governed by the cell envelope stress response. This observation was validated by orthologous approaches that demonstrate that a central player of this response, SigE, is both necessary and sufficient for potentiation of pyrazinamide action. Moreover, constitutive activation of this response through deletion of the anti-sigma factor gene rseA or exposure of bacilli to drugs that target the cell wall was found to potently drive pyrazinamide susceptibility independent of environmental pH. These findings force a paradigm shift in our understanding of pyrazinamide action and open new avenues for improving diagnostic and therapeutic tools for tuberculosis.

Original languageEnglish (US)
Article numbere00439
Issue number1
StatePublished - Feb 1 2022

Bibliographical note

Funding Information:
This study was supported by funds from the National Institutes of Health (AI123146 to A.D.B.). N.A.D was supported by training grant HL007741. R.A was supported by funds from West African Centre for Cell Biology of Infectious Pathogens, University of Ghana (Masters fellowship) under the mentorship of Lydia Mosi. S.J.M. and F.V. were supported by National Institute of Allergy and Infectious Diseases grant R01AI105185.

Publisher Copyright:
Copyright © 2022 Thiede et al.


  • Cell envelope
  • Drug discovery
  • Drug resistance mechanisms
  • Genomics
  • Metabolism
  • Tuberculosis

PubMed: MeSH publication types

  • Journal Article
  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural


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