# Transport across two membranes by AcrAB-TolC

> **NIH NIH R01** · UNIVERSITY OF OKLAHOMA · 2021 · $493,833

## Abstract

Project Description
Multidrug efflux pumps as exemplified by AcrAB-TolC from Escherichia coli are the major contributors to clinical
antibiotic resistance in bacteria and to various adaptive responses during pathogenesis and chronic infections.
During the previous funding period, we made major advances in two areas: 1) understanding the molecular
mechanism of efflux pump assembly and the role of periplasmic membrane fusion proteins in multidrug efflux
across two membranes; and 2) the development of a synergistic computational and empirical approach to
discovering efflux pump inhibitors with novel mechanisms of action. We successfully applied these advances to
discover inhibitors that act in a novel way, by interacting with AcrA and inhibiting the assembly of the AcrAB-
TolC complex. These efflux pump inhibitors potentiate activities of multiple antibiotics in various bacteria. The
major goal of the proposed research is to establish the molecular mechanisms of the new efflux pump inhibitors
and to optimize these inhibitors for use in combination with specific antibiotics and against specific multidrug
resistant bacteria. The underlying hypothesis is that the broad potentiation activity of the discovered inhibitors is
caused by their unique mechanism that traps efflux pumps in a poorly assembled and leaky conformation. In the
proposed approach, biochemical, structural and kinetic experiments will be used synergistically with advanced
computations to characterize the mechanism of efflux pump inhibitors and to optimize inhibitors acting on efflux
pumps of multidrug resistant Acinetobacter baumannii. To optimize inhibitors, we will apply what is to our
knowledge the most comprehensive platform available. The platform utilizes a set of strains with variable efflux
capacities and outer membrane permeability barriers and allows to establish structure-activity relationships
separately for efflux avoidance, inhibition and permeation across the outer membrane. Successful completion of
the proposed experiments will help design efflux pump inhibitors that would be effective even in the context of
multiple pumps and mechanisms of antibiotic resistance.

## Key facts

- **NIH application ID:** 10137173
- **Project number:** 5R01AI052293-17
- **Recipient organization:** UNIVERSITY OF OKLAHOMA
- **Principal Investigator:** HELEN I ZGURSKAYA
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $493,833
- **Award type:** 5
- **Project period:** 2003-03-01 → 2025-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10137173

## Citation

> US National Institutes of Health, RePORTER application 10137173, Transport across two membranes by AcrAB-TolC (5R01AI052293-17). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10137173. Licensed CC0.

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