Chemotactic-signal transducers respond to changes in the concentration of attractants and repellents in the environment, transduce a signal from the outside to the inside of the cell, and facilitate sensory adaptation through the variation of the level of methylation. TlpQ is a chemoreceptor that binds and mediates chemotaxis to histamine, a key biological signaling molecule. It binds histamine with high affinity, which permits responses to very low histamine concentrations (PubMed:30425146). Chemotaxis to histamine may play a role in the virulence of P.aeruginosa by recruiting cells at the infection site and consequently modulating the expression of quorum-sensing-dependent virulence genes (Probable). TlpQ also binds and mediates chemotaxis to polyamines such as putrescine, spermidine, cadaverine, agmatine and ethylenediamine (PubMed:30425146). In addition, binds the quorum-sensing signal autoinducer 2 (AI-2), thus inducing chemotaxis toward AI-2 and biofilm formation (PubMed:33097715). Homotetramer. The pctABC-tlpQ deletion mutant is devoid of histamine chemotaxis over the entire concentration range (50 nM to 50 mM) (PubMed:30425146). Deletion of the gene significantly reduces chemotaxis to AI-2 (PubMed:33097715). Belongs to the methyl-accepting chemotaxis (MCP) protein family.