The diverse CheC‐type phosphatases: chemotaxis and beyond

SummaryA new class of protein phosphatases has emerged in the study of bacterial/archaeal chemotaxis, the CheC‐type phosphatases. These proteins are distinct and unrelated to the well‐known CheY‐P phosphatase CheZ, though they have convergently evolved to dephosphorylate the same target. The family contains a common consensus sequence D/S‐X3‐E‐X2‐N‐X22‐P that defines the phosphatase active site, of which there are often two per protein. Three distinct subgroups make up the family: CheC, FliY and CheX. Further, the CheC subgroup can be divided into three classes. Bacillus subtilis CheC typifies the first class and might function as a regulator of CheD. Class II CheCs likely function as phosphatases in systems other than chemotaxis. Class III CheCs are found in the archaeal class Halobacteria and might function as class I CheCs. FliY is the main phosphatase in the B. subtilis chemotaxis system. CheX is quite divergent from the rest of the family, forms a dimer and some may function outside chemotaxis. A model for the evolution of the family is discussed.