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

• Main Authors: Raghunathan, Devanathan, Gayen, Shovanlal, Kumar, Anil, Hunke, Cornelia, Grüber, Gerhard, Verma, Chandra S.
• Other Authors: School of Biological Sciences
• Format: Article
• Language: English
• Published: 2013
• Subjects: DRNTU::Science::Biological sciences
• Online Access: https://hdl.handle.net/10356/104723; http://hdl.handle.net/10220/17008
• Institution: Nanyang Technological University

The interaction of the nucleotide-binding subunit B with subunit F is essential in coupling of ion pumping and ATP synthesis in A1AO 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 A1AO 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.