INVESTIGATION OF TRANSPHOSPHORYLATION BETWEEN CHEMOTAXIS PROTEINS ANDTHE PHOSPHOENOLPYRUVATE - SUGAR PHOSPHOTRANSFERASE SYSTEM

Transphosphorylation between the chemotaxis proteins and phosphoenolpy ruvate :sugar phosphotransferase system (PTS) from Escherichia coli wa s investigated by incubating the CheA, CheW and CheY proteins of the c hemotaxis cascade, and Enzyme I, HPr and Enzyme IImtl of the PTS with [gamma-P-32]ATP or [P-32]phosphoenolpyruvate in the presence and absen ce of cell extract, In the absence of cell extract, ATP phosphorylated CheA, but in the presence of cell extract, Enzyme I was also phosphor ylated, Phosphoenolpyruvate phosphorylated only PTS components, The tr ansphosphorylation of Enzyme I by ATP did not require chemotaxis prote ins, and likely occurred through acetate kinase, Regardless of phospho rylation state, the HPr protein did not inhibit the rate of ATP-depend ent phosphorylation of the CheA or the CheY protein. It is concluded t hat chemotaxis to PTS substrates is not mediated by transphosphorylati on between the PTS and chemotaxis systems.