Evaluation of CpxRA as a Therapeutic Target for Uropathogenic Escherichia coli Infections.

CpxRA is an envelope stress response system found in all members of the family ; CpxA has kinase activity for CpxR and phosphatase activity for phospho-CpxR, a transcription factor. CpxR also accepts phosphate groups from acetyl phosphate, a glucose metabolite. Activation of CpxR increases the transcription of genes encoding membrane repair and downregulates virulence determinants. We hypothesized that activation of CpxR could serve as an antimicrobial/antivirulence strategy and discovered compounds that activate CpxR in by inhibiting CpxA phosphatase activity. As a prelude to testing such compounds , here we constructed (in the presence of glucose, CpxR is activated because of a lack of CpxA phosphatase) and (system absent) deletion mutants of uropathogenic (UPEC) CFT073. By RNA sequencing, few transcriptional differences were noted between the mutant and its parent, but in the mutant, several UPEC virulence determinants were downregulated, including the and operons, and it exhibited reduced mannose-sensitive hemagglutination of guinea pig red blood cells In competition experiments with mice, both mutants were less fit than the parent in the urine, bladder, and kidney; these fitness defects were complemented in Unexpectedly, in single-strain challenges, only the mutant was attenuated for virulence in the kidney but not in the bladder or urine. For the mutant, this may be due to the preferential use of amino acids over glucose as a carbon source in the bladder and urine by UPEC. These studies suggest that CpxA phosphatase inhibitors may have some utility for treating complex urinary tract infections.