Conserved C-terminus of the phosphatase CheZ is a binding domain for the chemotactic response regulator CheY

CheZ is the phosphatase of the chemotactic response regulator, CheY. There are three conserved domains on CheZ. Here we determined the function of the C-terminal domain (residues 202-214). A truncated form of CheZ, missing residues 202-214, hardly bound to the phosphorylated form of CheY. Conversely, a peptide composed of the last 19 amino acid residues of the CheZ (residues 196-214), generated by tryptic digestion, bound specifically to the phosphorylated form of CheY. This was demonstrated by both fluorescence depolarization of the peptide (labeled with fluorescein) and cross-linking. It is concluded that the conserved C-terminus of CheZ functions as a CheY-binding domain.