Identification of the esterase peptide and its interaction with the cheZ peptide in bacterial sensing

Previous genetic evidence has indicated that the methylesterase activity of the chemotaxis system in Escherichia coli and Salmonella typhimurium resides with the cheB gene product, and that this protein may interact with the cheZ protein. In this article we report biochemical evidence for association of the cheB protein with esterase activity. We also show that while the cheZ gene product is not needed for catalysis, certain mutations in it can eliminate esterase activity in vitro, suggesting association of cheZ and cheB in an oligomeric protein complex.