The missing link between thermodynamics and structure in F1-ATPase

Area of Science:

• Biochemistry
• Molecular Biology
• Enzymology

Background:

• F(1)F(o)-ATP synthase is crucial for cellular energy production via ATP synthesis.
• Its catalytic domain, F(1)-ATPase, can also hydrolyze ATP.
• Linking experimental binding affinities to crystal structure conformations of MF(1) catalytic subunits (beta(TP), beta(DP), beta(E)) remains a challenge.

Purpose of the Study:

• To elucidate the relationship between ligand binding affinities and catalytic subunit conformations in MF(1).
• To identify the specific roles of beta(TP) and beta(DP) sites in ATP binding and hydrolysis.
• To understand the contribution of specific residues to the enzyme's catalytic mechanism.

Main Methods:

• Free energy difference simulations for ATP hydrolysis reaction (ATP+H(2)O --> ADP+P(i)).
• Unisite hydrolysis data analysis.
• Energy decomposition analysis of catalytic residues.

Main Results:

• Identified beta(TP) as the high-affinity ATP binding site (K(D) = 10(-12) M) and beta(DP) as a lower-affinity site.
• Energy decomposition revealed how specific residues modulate hydrolysis free energy in both sites despite structural similarity.
• Results provide atomic-level insights into the MF(1) binding change mechanism.

Conclusions:

• The study successfully links experimental binding data with structural conformations of MF(1).
• Provides a detailed atomic-level understanding of the F(1)-ATPase binding change mechanism.
• Highlights the role of specific residues in modulating enzyme catalysis and ligand binding.