# Cell envelope stress responses and the mechanism of antibiotic tolerance in Gram-negative pathogens

> **NIH NIH R01** · CORNELL UNIVERSITY · 2020 · $392,639

## Abstract

Project Summary
Bacteria often resist killing by normally bactericidal antibiotics, resulting in clinical treatment failure and the
development of antibiotic resistance. The ability to survive damage elicited by exposure to antibiotics is termed
tolerance. Tolerance is likely responsible for the recurrence of infections after discontinuation of antimicrobial
therapy, and provides a reservoir of a bacterial population that can develop full scale resistance. An extreme
case of tolerance is the formation of persister cells, which do not experience antibiotic-induced damage due to
dormancy. However, we and others have found that many Gram-negative pathogens (Vibrio cholerae,
Pseudomonas aeruginosa, Enterobacter cloacae, Haemophilus influenzae and Acinetobacter baumannii) are
fully susceptible to damage induced by cell wall acting antibiotics (beta lactams), but yet survive at very high
levels. Survival is enabled through the formation of viable spheres that are devoid of detectable cell wall
material and that recover to normal shape upon withdrawal of the antibiotic. In our model organism, the cholera
pathogen V. cholerae, tolerance is promoted by cell envelope stress responses, especially the two-component
system WigKR. WigKR is induced by cell wall acting antibiotics and mounts a complex response that ultimately
enables recovery from the spherical state. This response includes upregulation of cell wall synthesis functions,
outer membrane synthesis, phospholipid synthesis and downregulation of motility and iron acquisition genes.
How this response promotes tolerance is poorly understood, and so are the mechanisms of tolerance in other
Gram-negative bacteria. Here, we aim to interrogate V. cholerae's cell envelope stress responses and their
relationship with beta lactam tolerance and post-antibiotic recovery. Using genetic and biochemical
approaches, we will find the elusive induction signal sensed by the histidine kinase WigK. Leveraging
extensive datasets comprehensively describing the WigKR regulon, we will measure each individual regulon
member's contribution to beta lactam tolerance. Lastly, we will apply what we have learned in the V. cholerae
model to other Gram-negative pathogens exhibiting high beta lactam tolerance, specifically E. cloacae and P.
aeruginosa. Our experiments will yield novel insight into the mechanisms of antibiotic tolerance and result in
the identification of candidate drug targets for anti-tolerance adjuvants of beta lactams.

## Key facts

- **NIH application ID:** 9849186
- **Project number:** 5R01AI143704-02
- **Recipient organization:** CORNELL UNIVERSITY
- **Principal Investigator:** Tobias Doerr
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $392,639
- **Award type:** 5
- **Project period:** 2019-01-10 → 2023-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9849186

## Citation

> US National Institutes of Health, RePORTER application 9849186, Cell envelope stress responses and the mechanism of antibiotic tolerance in Gram-negative pathogens (5R01AI143704-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9849186. Licensed CC0.

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