Crystal Structure of the Mg•ADP-inhibited State of the Yeast F1c10-ATP Synthase

The F(1)c(10) subcomplex of the yeast F1F0-ATP synthase includes the membrane rotor part c(10)-ring linked to a catalytic head, (alpha beta)(3), by a central stalk, gamma delta epsilon. The Saccharomyces cerevisiae yF(1)c(10).ADP subcomplex was crystallized in the presence of Mg center dot ADP, dicyclohexylcarbodiimide (DCCD), and azide. The structure was solved by molecular replacement using a high resolution model of the yeast F-1 and a bacterial c-ring model with 10 copies of the c-subunit. The structure refined to 3.43-angstrom resolution displays new features compared with the original yF(1)c(10) and with the yF1 inhibited by adenylyl imidodiphosphate (AMP-PNP) (yF(1)(I-III)). An ADP molecule was bound in both beta(DP) and beta(TP) catalytic sites. The alpha(DP)-beta(DP) pair is slightly open and resembles the novel conformation identified in yF(1), whereas the alpha(TP)-beta(TP) pair is very closed and resembles more a DP pair. yF(1)c(10) ADP provides a model of a new Mg center dot ADP-inhibited state of the yeast F-1. As for the original yF(1) and yF(1)c(10) structures, the foot of the central stalk is rotated by similar to 40 degrees with respect to bovine structures. The assembly of the F-1 central stalk with the F(0)c-ring rotor is mainly provided by electrostatic interactions. On the rotor ring, the essential cGlu(59) carboxylate group is surrounded by hydrophobic residues and is not involved in hydrogen bonding.