Conformational dynamics of the rotary subunit F in the A 3 B 3 DF complex of Methanosarcina mazei Gö1 A‐ ATP synthase monitored by single‐molecule FRET

In archaea the A 1 A O ATP synthase uses a transmembrane electrochemical potential to generate ATP , while the soluble A 1 domain (subunits A 3 B 3 DF ) alone can hydrolyse ATP . The three nucleotide‐binding AB pairs form a barrel‐like structure with a central orifice that hosts the rotating central stalk subunits DF. ATP binding, hydrolysis and product release cause a conformational change inside the A:B‐interface, which enforces the rotation of subunits DF. Recently, we reported that subunit F is a stimulator of ATP ase activity. Here, we investigated the nucleotide‐dependent conformational changes of subunit F relative to subunit D during ATP hydrolysis in the A 3 B 3 DF complex of the Methanosarcina mazei Gö1 A‐ ATP synthase using single‐molecule Förster resonance energy transfer. We found two conformations for subunit F during ATP hydrolysis.