Subunit F modulates ATP binding and migration in the nucleotide-binding subunit B of the A1AO ATP synthase of Methanosarcina mazei Gö1

• Published in: Journal of bioenergetics and biomembranes Vol. 44; no. 1; pp. 213 - 224
• Main Authors: Raghunathan, Devanathan, Gayen, Shovanlal, Kumar, Anil, Hunke, Cornelia, Grüber, Gerhard, Verma, Chandra S.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.02.2012
• Subjects: Animal Anatomy; Animal Biochemistry; Biochemistry; Bioorganic Chemistry; Chemistry; Chemistry and Materials Science; Histology; Morphology; Organic Chemistry; A; ATP synthase; Subunit B; Fluorescence correlation spectroscopy (FCS); Isothermal titration calorimetry (ITC); Molecular dynamics simulations; ATP; Nuclear magnetic resonance (NMR)
• ISSN: 0145-479X; 1573-6881
• DOI: 10.1007/s10863-012-9410-y

The interaction of the nucleotide-binding subunit B with subunit F is essential in coupling of ion pumping and ATP synthesis in A 1 A O ATP synthases. Here we provide structural and thermodynamic insights on the nucleotide binding to the surface of subunits B and F of Methanosarcina mazei Gö1 A 1 A O ATP synthase, which initiated migration to its final binding pocket via two transitional intermediates on the surface of subunit B. NMR- and fluorescence spectroscopy as well as ITC data combined with molecular dynamics simulations of the nucleotide bound subunit B and nucleotide bound B-F complex in explicit solvent, suggests that subunit F is critical for the migration to and eventual occupancy of the final binding site by the nucleotide of subunit B. Rotation of the C-terminus and conformational changes in subunit B are initiated upon binding with subunit F causing a perturbation that leads to the migration of ATP from the transition site 1 through an intermediate transition site 2 to the final binding site 3. This mechanism is elucidated on the basis of change in binding affinity for the nucleotide at the specific sites on subunit B upon complexation with subunit F. The change in enthalpy is further explained based on the fluctuating local environment around the binding sites.