Involved in chemotaxis. Part of a chemotaxis signal transduction system that modulates chemotaxis in response to various stimuli. Catalyzes the demethylation of specific methylglutamate residues introduced into the chemoreceptors (methyl-accepting chemotaxis proteins or MCP) by CheR. Also mediates the irreversible deamidation of specific glutamine residues to glutamic acid (By similarity) (PubMed:12142407). Acts on the methyl-accepting chemotaxis protein McpB (Probable). May be involved in a specific chemotactic response, which takes place during infection and is required for P.aeruginosa pathogenicity (PubMed:19662168). [protein]-L-glutamate 5-O-methyl ester + H2O = H(+) + L-glutamyl-[protein] + methanol H2O + L-glutaminyl-[protein] = L-glutamyl-[protein] + NH4(+) Interacts with the C-terminal pentapeptide GWEEF of McpB. Contains a C-terminal catalytic domain, and an N-terminal region which modulates catalytic activity. Phosphorylated by CheA. Phosphorylation of the N-terminal regulatory domain activates the methylesterase activity. Mutant is defective in chemotaxis, but does not have an obvious defect in swimming behavior (PubMed:12142407). Mutant shows strongly reduced adherence to a biological surface such as the human epithelial cell line, and a reduction in swimming motility (PubMed:19662168). Also shows a highly attenuated virulence in C.elegans and in a murine lung infection model, and fails to induce strong inflammatory response in the infected mice lungs (PubMed:19662168). This protein is able to restore chemotaxis to a completely non-chemotactic CheB1 mutant to near wild-type levels. Belongs to the CheB family.