Association of 14-3-3 proteins with the C-terminal antoinhibitory domain of the plant plasma-membrane H+-ATPase generates a fusicoccin-binding complex

The plant plasma-membrane H+-ATPase (EC 3.6.1.35) contains a C-terminal autoinhibitory domain whose displacement from the catalytic site is caused by treatment of intact plant tissue with the phytotoxin fusicoccin (FC). The FC-induced activation of the H+-ATPase was proposed to involve a direct interaction of 14-3-3 proteins with the H+-ATPase. By analysing plasma membranes derived from leaves of Commelina communis L., direct biochemical evidence has now been obtained for a complex between the C-terminus of the H+-ATPase and a 14-3-3 dimer. Stabilization of this complex was achieved by FC treatment in vivo or in vitro. Furthermore, the C-terminal domain of the H+-ATPase in association with a 14-3-3 dimer is essential for the creation of a functional FC-binding complex.