The small molecule regacin binds a conserved pocket in RegA to inhibit the expression of bacterial virulence factors
- 1Dartmouth College
Abstract
Antivirulence therapeutics are a promising strategy to combat rising antimicrobial resistance. Transcription factor proteins have shown merit as antivirulence drug targets, as demonstrated by the small molecule Savirin. Regacin was identified as a potent inhibitor of the AraC-family virulence regulator (AraC-VR) RegA of Citrobacter rodentium, providing proof-of-concept for targeting AraC-VR family members in related human enteric pathogens. The structural basis of RegA inhibition by regacin was previously undefined and could prove essential for future drug design campaigns targeting AraC-VR family members. This work reveals that RegA is structurally similar to its homologs ToxT and Rns, including a conserved ligand-binding pocket in the N-terminal domain. A regacin-RegA co-crystal structure shows regacin binds within this pocket, with some heterogeneity in binding pose. Finally, structure-guided mutagenesis of key pocket residues, validated using a {beta}-galactosidase reporter assay, confirmed their role in regacin-mediated inhibition. Together, these findings define the regacin binding site, suggest a molecular basis of RegA inhibition, and provide a framework for future inhibitor design targeting this conserved pocket in other virulence regulators in human enteric pathogens.
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BibTeX
@misc{bollinger2026small,
title = {{The small molecule regacin binds a conserved pocket in RegA to inhibit the expression of bacterial virulence factors}},
author = {C. M. Bollinger and C. R. Midgett and K. M. Talbot and G. V. Lawhern and G. Munson},
howpublished = {bioRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.11.750636},
url = {https://www.biorxiv.org/content/10.64898/2026.09.11.750636v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - The small molecule regacin binds a conserved pocket in RegA to inhibit the expression of bacterial virulence factors
AU - C. M. Bollinger
AU - C. R. Midgett
AU - K. M. Talbot
AU - G. V. Lawhern
AU - G. Munson
PY - 2026
DA - 2026/09/11
PB - bioRxiv
DO - 10.64898/2026.09.11.750636
UR - https://www.biorxiv.org/content/10.64898/2026.09.11.750636v1
AB - Antivirulence therapeutics are a promising strategy to combat rising antimicrobial resistance. Transcription factor proteins have shown merit as antivirulence drug targets, as demonstrated by the small molecule Savirin. Regacin was identified as a potent inhibitor of the AraC-family virulence regulator (AraC-VR) RegA of Citrobacter rodentium, providing proof-of-concept for targeting AraC-VR family members in related human enteric pathogens. The structural basis of RegA inhibition by regacin was previously undefined and could prove essential for future drug design campaigns targeting AraC-VR family members. This work reveals that RegA is structurally similar to its homologs ToxT and Rns, including a conserved ligand-binding pocket in the N-terminal domain. A regacin-RegA co-crystal structure shows regacin binds within this pocket, with some heterogeneity in binding pose. Finally, structure-guided mutagenesis of key pocket residues, validated using a {beta}-galactosidase reporter assay, confirmed their role in regacin-mediated inhibition. Together, these findings define the regacin binding site, suggest a molecular basis of RegA inhibition, and provide a framework for future inhibitor design targeting this conserved pocket in other virulence regulators in human enteric pathogens.
ER -