Pseudomonas aeruginosa Performs Chemotaxis to All Major Human Neurotransmitters

The ubiquitous pathogen Pseudomonas aeruginosa is attracted to γ-aminobutyrate (GABA), acetylcholine, histamine, serotonin, epinephrine, norepinephrine, dopamine, tyramine, glycine, and glutamate via chemotaxis. These compounds are all major neurotransmitters in humans. They are also found in various non-neuronal tissues and are synthesised by different organisms, including bacteria, protozoa, invertebrates, and plants. Many of these neurotransmitters increase the expression of virulence-related genes in P. aeruginosa, so that chemotaxis to these compounds may constitute an important virulence factor. The chemotactic response is initiated by the direct binding of these compounds to the dCache ligand-binding domains of the PctC, TlpQ, PctD, PctA, and PctB chemoreceptors. Previous studies have shown that Escherichia coli is attracted to epinephrine, norepinephrine, and dopamine. These responses are mediated by the Tar and Tsr chemoreceptors, which possess four-helix bundle-type ligand-binding domains. The use of structurally dissimilar chemoreceptors to mediate neurotransmitter chemotaxis suggests convergent evolution. This article is intended to stimulate the study of the connection between neurotransmitter chemotaxis and virulence in P. aeruginosa and to expand the search for neurotransmitter chemotaxis in other motile bacteria.