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

Abstract

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.

Phosphatase activity of the control of virulence sensor kinase CovS is critical for the pathogenesis of group A streptococcus

“…The Spinola group has suggested the use of phosphatase inhibitors towards histidine kinase CpxA to treat certain urinary tract infections caused by uropathogenic E . coli [ 73 , 74 ]. These examples corroborate the importance of HK phosphatase activity in bacterial virulence and suggest a broader application of this approach with regards to other histidine kinases in pathogen bacteria.…”

The Yersinia pseudotuberculosis Cpx envelope stress system contributes to transcriptional activation of rovM

“…This choice was motivated by several telling reasons. First, late stationary phase allows for the cpxA deletion to accumulate phosphorylated CpxR [11]. Second, transcriptome analyses of CpxR-regulated genes have consistently shown maximal activation of the Cpx pathway in bacteria grown to late stationary phase [11,34,84].…”

“…First, late stationary phase allows for the cpxA deletion to accumulate phosphorylated CpxR [11]. Second, transcriptome analyses of CpxR-regulated genes have consistently shown maximal activation of the Cpx pathway in bacteria grown to late stationary phase [11,34,84]. Third, maximal rovM expression in Yersinia occurs at late stationary phase when nutrients needed for growth have been exhausted [56,62,64,65].…”

“…Upon sensing ECSs, CpxA is first an autokinase and then a phosphoryl donor to CpxR. Based upon available genome-wide transcriptome data, phosphorylated CpxR (CpxR~P) then acts as a transcription factor to activate or repress~100 gene targets in bacteria [8][9][10][11]. Among these are a number of small regulatory RNAs [9], including the newly described regulatory RNA, CpxQ, which works together with the Hfq protein to repress mRNAs of envelope proteins [12,13].…”

“…Intriguingly, it is now also apparent that an intact Cpx signalling pathway is essential for full virulence of diverse clinically-and agriculturally-relevant bacteria most probably because CpxR~P can influence the levels of virulence gene expression [11,[18][19][20][21][22][23][24][25]. These findings are being exploited with the purpose of identifying small molecule modulators of the Cpx response that could be used as novel virulence blockers [26].…”