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J Infect Dis. 2016 Apr 15;213(8):1330-9. doi: 10.1093/infdis/jiv584. Epub 2015 Dec 15.

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

Author information

1
Department of Pediatrics.
2
Department of Molecular Genetics and Microbiology.
3
Specialized Chemistry Center, University of Kansas, Lawrence.
4
Department of Pediatrics Department of Molecular Genetics and Microbiology Center for Microbial Pathogenesis, Duke University School of Medicine, Durham, North Carolina.

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.

KEYWORDS:

E. coli; multidrug efflux pumps; polysaccharide capsule; small-molecule capsule inhibitor

PMID:
26671885
PMCID:
PMC4799666
DOI:
10.1093/infdis/jiv584
[Indexed for MEDLINE]
Free PMC Article

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