Structural analysis of ATP bound to the F1-ATPase β-subunit monomer by solid-state NMR- insight into the hydrolysis mechanism in F1

ATP-hydrolysis-associated conformational change of the β-subunit during the rotation of F₁-ATPase (F₁) has been discussed using cryo-electron microscopy (cryo-EM). Since it is worthwhile to further investigate the conformation of ATP at the catalytic subunit through an alternative approach, the structure of ATP bound to the F₁β-subunit monomer (β) was analyzed by solid-state NMR. The adenosine conformation of ATP-β was similar to that of ATP analog in F₁ crystal structures. ³¹P chemical shift analysis showed that the P^α and P^β conformations of ATP-β are gauche-trans and trans-trans, respectively. The triphosphate chain is more extended in ATP-β than in ATP analog in F₁ crystals. This appears to be in the state just before ATP hydrolysis. Furthermore, the ATP-β conformation is known to be more closed than the closed form in F₁ crystal structures. In view of the cryo-EM results, ATP-β would be a model of the most closed β-subunit with ATP ready for hydrolysis in the hydrolysis stroke of the F₁ rotation.