title: Mechanism of the conformational change of the F1-ATPase β subunit revealed by free energy simulations.
abstract: F(1)-ATPase is an ATP-driven rotary motor enzyme. The β subunit changes its conformation from an open to a closed form upon ATP binding. The motion in the β subunit is regarded as a major driving force for rotation of the central stalk. In this Article, we explore the conformational change of the β subunit using all-atom free energy simulations with explicit solvent and propose a detailed mechanism for the conformational change. The β subunit conformational change is accomplished roughly in two characteristic steps: changing of the hydrogen-bond network around ATP and the dynamic movement of the C-terminal domain via sliding of the B-helix. The details of the former step agree well with experimental data. In the latter step, sliding of the B-helix enhances the hydrophobic stabilization due to the exclusion of water molecules from the interface and improved packing in the hydrophobic core. This step contributes to a decrease in free energy, leading to the generation of torque in the F(1)-ATPase upon ATP binding.
authors.affiliation: Graduate School of Nanobioscience, Yokohama City University, 1-7-29, Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Ito
authors.forename: Tomotaka
authors.initials: T
authors.lastname: Oroguchi
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Ikeguchi
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry*; D018360:Crystallography, X-Ray; D019277:Entropy; D011487:Protein Conformation; D021122:Protein Subunits / Q000737:chemistry; D006180:Proton-Translocating ATPases / Q000737:chemistry*
chemical_list: D021122:Protein Subunits; D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases