CpxA Phosphatase Inhibitor Activates CpxRA and Is a Potential Treatment for Uropathogenic Escherichia coli in a Murine Model of Infection

Kate R. Fortney, Sara N. Smith, Julia J. van Rensburg, Julie A. Brothwell, Jessi J. Gardner, Barry P. Katz, Nagib Ahsan, Adam S. Duerfeldt, Harry L.T. Mobley, Stanley M. Spinola

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


CpxRA is an envelope stress response system that is highly conserved in the Enterobacteriaceae. CpxA has kinase activity for CpxR and phosphatase activity for phospho-CpxR (CpxR-P), a transcription factor. In response to membrane stress, CpxR-P is produced and upregulates genes involved in membrane repair and downregulates genes that encode virulence factors that are trafficked across the cell membrane. Mutants that constitutively activate CpxRA in Salmonella enterica serovar Typhimurium and in uropathogenic Escherichia coli (UPEC) are attenuated in murine models. We hypothesized that pharmacologic activation of CpxR could serve as an antimicrobial/antivirulence strategy and recently showed that 2,3,4,9-tetrahydro-1H-carbazol-1-amines activate the CpxRA system by inhibiting CpxA phosphatase activity. Here, we tested the ability of a series of three CpxRA-activating compounds with increasing potency to clear UPEC stain CFT073 in a murine urinary tract infection model. We show that these compounds are well tolerated and achieve sufficient levels to activate CpxR in the kidneys, bladder, and urine. Although the first two compounds were ineffective in promoting clearance of CFT073 in the murine model, the most potent derivative, compound 26, significantly reduced bacterial recovery in the urine and trended toward reducing bacterial recovery in the bladder and kidneys, with efficacy similar to ciprofloxacin. Treatment of CFT073 cultured in human urine with compound 26 fostered accumulation of CpxR-P and decreased the expression of proteins involved in siderophore biosynthesis and binding, heme degradation, and flagellar movement. These studies suggest that chemical activation of CpxRA may present a viable strategy for treating infections due to UPEC. IMPORTANCE The increasing prevalence of urinary tract infections (UTIs) due to antibiotic-resistant uropathogenic Escherichia coli (UPEC) is a major public health concern. Bacteria contain proteins that sense their environment and have no human homologs and, thus, are attractive drug targets. CpxRA is a conserved sensing system whose function is to reduce stress in the bacterial cell membrane; activation of CpxRA reduces the expression of virulence determinants, which must cross the cell membrane to reach the bacterial surface. We previously identified a class of compounds that activate CpxRA. We show in a mouse UTI model that our most potent compound significantly reduced recovery of UPEC in the urine, trended toward reducing bacterial recovery in the bladder and kidneys, did not kill UPEC, and downregulated multiple proteins involved in UPEC virulence. Since these compounds do not act by a killing mechanism, they have potential to treat UTIs caused by antibiotic-resistant bacteria.

Original languageEnglish (US)
JournalMicrobiology Spectrum
Issue number2
StatePublished - Apr 2022

Bibliographical note

Funding Information:
This project was funded with support from the IUPUI Funding Opportunities for Research Commercialization and Economic Success (FORCES), the Indiana Clinical and Translational Sciences Institute, which is funded in part by award number UL1TR002529 from the National Institutes of Health, National Center for Advancing Translational Sciences, Clinical and Translational Sciences Award, and R01AI27863 from the National Institute of Allergy and Infectious Diseases to S.M.S. and R01AI136795 to A.S.D.

Funding Information:
We thank the In Vivo Therapeutics Core and the Clinical Pharmacology Analytical Core at the Indiana University School of Medicine, which are supported by the IU Simon Comprehensive Cancer Center Support Grant P30 CA082709, for their assistance with the in vivo toxicology, PK, and mass spectrometry studies.

Publisher Copyright:
Copyright © 2022 Fortney et al.


  • CpxRA
  • Escherichia coli
  • UPEC
  • phosphatase inhibitor
  • treatment


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