The histidine kinase (HK) CheA relays signals from the transmembrane chemoreceptors (methyl-accepting chemotaxis proteins/MCPs) to regulate bacterial chemotaxis. The functional form of CheA exists as a dimer and is associated to the receptors through a coupling protein CheW. Kinase activity of CheA depends on signals received from the receptor via an ATP-dependent phosphoryl transfer the trans monomer of dimeric CheA. The phosphoryl group is subsequently transferred to the response regulator (RR) CheY and carried throughout the cell to interact with the flagellar motor and control cellular mobility and directionality.
