Structural evidence of a new catalytic intermediate in the pathway of ATP hydrolysis by F1-ATPase from bovine heart mitochondria.

TitleStructural evidence of a new catalytic intermediate in the pathway of ATP hydrolysis by F1-ATPase from bovine heart mitochondria.
Publication TypeJournal Article
Year of Publication2012
AuthorsRees, DM, Montgomery, MG, Leslie, AGW, Walker, JE
JournalProc Natl Acad Sci U S A
Volume109
Issue28
Pagination11139-43
Date Published2012 Jul 10
ISSN1091-6490
KeywordsAdenosine Diphosphate, Adenosine Triphosphate, Animals, Binding Sites, Catalysis, Cattle, Crystallography, X-Ray, Hydrolysis, Ions, Magnesium, Mitochondria, Heart, Models, Chemical, Models, Molecular, Molecular Conformation, Nucleotides, Protein Structure, Tertiary, Proton-Translocating ATPases, Water
Abstract

The molecular description of the mechanism of F(1)-ATPase is based mainly on high-resolution structures of the enzyme from mitochondria, coupled with direct observations of rotation in bacterial enzymes. During hydrolysis of ATP, the rotor turns counterclockwise (as viewed from the membrane domain of the intact enzyme) in 120° steps. Because the rotor is asymmetric, at any moment the three catalytic sites are at different points in the catalytic cycle. In a "ground-state" structure of the bovine enzyme, one site (β(E)) is devoid of nucleotide and represents a state that has released the products of ATP hydrolysis. A second site (β(TP)) has bound the substrate, magnesium. ATP, in a precatalytic state, and in the third site (β(DP)), the substrate is about to undergo hydrolysis. Three successive 120° turns of the rotor interconvert the sites through these three states, hydrolyzing three ATP molecules, releasing the products and leaving the enzyme with two bound nucleotides. A transition-state analog structure, F(1)-TS, displays intermediate states between those observed in the ground state. For example, in the β(DP)-site of F(1)-TS, the terminal phosphate of an ATP molecule is undergoing in-line nucleophilic attack by a water molecule. As described here, we have captured another intermediate in the catalytic cycle, which helps to define the order of substrate release. In this structure, the β(E)-site is occupied by the product ADP, but without a magnesium ion or phosphate, providing evidence that the nucleotide is the last of the products of ATP hydrolysis to be released.

DOI10.1073/pnas.1207587109
Alternate JournalProc. Natl. Acad. Sci. U.S.A.
Citation Key10.1073/pnas.1207587109
PubMed ID22733764
PubMed Central IDPMC3396519
Grant ListMC_U105184325 / / Medical Research Council / United Kingdom
MC_U105663150 / / Medical Research Council / United Kingdom
/ / Medical Research Council / United Kingdom