Deamidates glutamine residues to glutamate on methyl-accepting chemotaxis receptors (MCPs). CheD-mediated MCP deamidation is required for productive communication of the conformational signals of the chemoreceptors to the CheA kinase (By similarity). H2O + L-glutaminyl-[protein] = L-glutamyl-[protein] + NH4(+) Forms a complex with CheC. Belongs to the CheD family.