Chemoreceptor that plays a critical role in the virulence and pathogenesis of P.aeruginosa in a variety of hosts (PubMed:31511598). Probably acts through oxygen sensing (PubMed:31511598, PubMed:28167524, PubMed:34383467). Uses a heme-based sensor (PubMed:21255112, PubMed:22622145). Could be involved in chemotaxis (PubMed:12142407, PubMed:14987771). When expressed in E.coli, is able to sense and mediate repellent responses to oxygen, carbon monoxide and nitric oxide (PubMed:21255112). Homodimer (PubMed:21255112, PubMed:23274111, PubMed:34383467). The PAS domains form dimers in the presence and absence of oxygen (PubMed:34383467). Interacts with the methyltransferase CheR2 via the C-terminal McpB pentapeptide GWEEF (PubMed:24714571). Interacts with the methylesterase/gutaminase CheB2, which also binds to the GWEEF pentapeptide (PubMed:33187094). Expression is regulated by the sigma factor RpoS. Contains five HAMP domains, three at the N-terminus and two at the C-terminus, separated by a PAS-sensing domain (PubMed:20399181). The PAS domain binds penta-coordinated b-type heme and is likely responsible for sensing the gases (PubMed:21255112, PubMed:28167524). Binding of oxygen induces conformational changes in the PAS-heme domain (PubMed:34383467). The N-terminal HAMP domains facilitate the O(2)-dependent shift of PAS to the signal-on conformation (PubMed:34383467). Signals propagate from the PAS domain to the C-terminal HAMP domains via a conserved DxT motif (PubMed:34383467). PAS and HAMP domains do not directly interact but are arranged in a linear fashion (PubMed:23274111). Methylated by CheR2, but not by CheR1, CheR3 or WspC (PubMed:24714571). Demethylated by CheB2 (Probable). In vitro, can be methylated by E.coli CheR (PubMed:21255112). The deletion of the gene results in an attenuation of bacterial virulence in different infection models in species as diverse as C.elegans, E.foetida or the insects A.bipunctata and C.carnae (PubMed:31511598). Mutants have general chemotaxis defects (PubMed:12142407). Mutant shows decreased aerotaxis (PubMed:14987771). Aerotaxis is abolished in the aer-mcpB double mutant (PubMed:14987771). Belongs to the methyl-accepting chemotaxis (MCP) protein family.