title: Threading the Needle: Small-Molecule Targeting of a Xenobiotic Receptor to Ablate Escherichia coli Polysaccharide Capsule Expression Without Altering Antibiotic Resistance.
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.
authors.affiliation: Department of Pediatrics.
authors.forename: Mehreen
authors.initials: M
authors.lastname: Arshad
authors.affiliation: Department of Pediatrics.
authors.forename: Carlos C
authors.initials: CC
authors.lastname: Goller
authors.affiliation: Department of Molecular Genetics and Microbiology.
authors.forename: Danielle
authors.initials: D
authors.lastname: Pilla
authors.affiliation: Specialized Chemistry Center, University of Kansas, Lawrence.
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Schoenen
authors.affiliation: Department of Pediatrics Department of Molecular Genetics and Microbiology Center for Microbial Pathogenesis, Duke University School of Medicine, Durham, North Carolina.
authors.forename: Patrick C
authors.initials: PC
authors.lastname: Seed
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D016667:Bacterial Capsules / Q000187:drug effects / Q000378:metabolism*; D004195:Disease Models, Animal; D055808:Drug Discovery / Q000379:methods*; D024901:Drug Resistance, Multiple, Bacterial; D004927:Escherichia coli Infections / Q000382:microbiology; D029968:Escherichia coli Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D005260:Female; D055785:Gene Knockdown Techniques / Q000379:methods*; D051379:Mice; D008810:Mice, Inbred C57BL; D012097:Repressor Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D056689:Uropathogenic Escherichia coli / Q000187:drug effects / Q000235:genetics*; D014774:Virulence
chemical_list: D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; D012097:Repressor Proteins; C093326:mprA protein, E coli
keywords: E. coli; multidrug efflux pumps; polysaccharide capsule; small-molecule capsule inhibitor