Threading the Needle: Small-Molecule Targeting of a Xenobiotic Receptor to Ablate Escherichia coli Polysaccharide Capsule Expression Without Altering Antibiotic Resistance

Mehreen Arshad, Carlos C. Goller, Danielle Pilla, Frank J. Schoenen, Patrick C. Seed*

*Corresponding author for this work

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

Background. Uropathogenic Escherichia coli (UPEC), a leading cause of urinary tract and invasive infections worldwide, is rapidly acquiring multidrug resistance, hastening the need for selective new anti-infective agents. Here we demonstrate the molecular target of DU011, our previously discovered potent, nontoxic, small-molecule inhibitor of UPEC polysaccharide capsule biogenesis and virulence. Methods. Real-time polymerase chain reaction analysis and a target-overexpression drug-suppressor screen were used to localize the putative inhibitor target. A thermal shift assay quantified interactions between the target protein and the inhibitor, and a novel DNase protection assay measured chemical inhibition of protein-DNA interactions. Virulence of a regulatory target mutant was assessed in a murine sepsis model. Results. MprA, a MarR family transcriptional repressor, was identified as the putative target of the DU011 inhibitor. Thermal shift measurements indicated the formation of a stable DU011-MprA complex, and DU011 abrogated MprA binding to its DNA promoter site. Knockout of mprA had effects similar to that of DU011 treatment of wild-type bacteria: a loss of encapsulation and complete attenuation in a murine sepsis model, without any negative change in antibiotic resistance. Conclusions. MprA regulates UPEC polysaccharide encapsulation, is essential for UPEC virulence, and can be targeted without inducing antibiotic resistance.

Original languageEnglish (US)
Pages (from-to)1330-1339
Number of pages10
JournalJournal of Infectious Diseases
Volume213
Issue number8
DOIs
StatePublished - Apr 15 2016

Keywords

  • E. Coli
  • multidrug efflux pumps
  • polysaccharide capsule
  • small-molecule capsule inhibitor

ASJC Scopus subject areas

  • Immunology and Allergy
  • Infectious Diseases

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