Figure 1:
Citrobacter rodentium can sense host neurochemical signals to regulate virulence. A) Epinephrine (Epi) and norepinephrine (NE) are sensed by QseC and QseE which lead to receptor autophosphorylation and subsequent expression of virulence genes. B) Serotonin induces dephosphorylation of the bacteria CpxA receptor, which, in turn, inactivates transcriptional factors required for virulence gene expression. C) The endocannabinoid 2-AG functions as a competitive antagonist of the QseC receptor, blocking Epi/NE interaction, and consequently, reducing CR virulence expression.