National Center for
3AON: Crystal Structure Of The Central Axis (Ntpd-Ntpg) In The Catalytic Portion Of Enterococcus Hirae V-Type Sodium Atpase
Proc. Natl. Acad. Sci. U. S. A. (2011) 108 p.19955-19960
V-ATPases function as ATP-dependent ion pumps in various membrane systems of living organisms. ATP hydrolysis causes rotation of the central rotor complex, which is composed of the central axis D subunit and a membrane c ring that are connected by F and d subunits. Here we determined the crystal structure of the DF complex of the prokaryotic V-ATPase of Enterococcus hirae at 2.0-A resolution. The structure of the D subunit comprised a long left-handed coiled coil with a unique short beta-hairpin region that is effective in stimulating the ATPase activity of V(1)-ATPase by twofold. The F subunit is bound to the middle portion of the D subunit. The C-terminal helix of the F subunit, which was believed to function as a regulatory region by extending into the catalytic A(3)B(3) complex, contributes to tight binding to the D subunit by forming a three-helix bundle. Both D and F subunits are necessary to bind the d subunit that links to the c ring. From these findings, we modeled the entire rotor complex (DFdc ring) of V-ATPase.