Function
Acts as an auxiliary protein in the Cpx two-component envelope stress response system, helping modulate the Cpx response systems response to some inducers (PubMed:25207645, PubMed:16303867). Binds the periplasmic domain of sensor histidine kinase CpxA, inhibiting induction of the Cpx envelope stress response in the absence of inducer; overexpression decreases Cpx pathway activity (PubMed:16166523, PubMed:21317318). Some periplasmic stimulii (shown for P pili subunit PapE and probably 0.3 M NaCl) increase CpxP's susceptibility to DegP, leading to CpxP degradation, inducing the Cpx pathway (PubMed:16166523, PubMed:16303867). Aids in combating extracytoplasmic protein-mediated toxicity (PubMed:9473036, PubMed:16303867, PubMed:21239493). Overexpression leads to degradation by DegP of misfolded P pili subunits in the periplasm (tested using PapE) (PubMed:21239493). Inhibits autophosphorylation of CpxA in reconstituted liposomes by 50% but has no effect on phosphatase activity of CpxA (PubMed:17259177, PubMed:21239493). Has mild protein chaperone activity (PubMed:21317898, PubMed:21239493).