Oral Presentation The 47th Lorne Conference on Protein Structure and Function 2022

The six steps of the complete F1-ATPase rotary catalytic cycle (#1)

Alastair G Stewart 1 2 , Meghna Sobti 1 2 , Hiroshi Ueno 3 , Hiroyuki Noji 3
  1. VCCRI, Darlinghurst, NSW, Australia
  2. Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia
  3. Graduate School of Engineering, The University of Tokyo, Tokyo, Japan

F1Fo ATP synthase interchanges phosphate transfer energy and proton motive force via a rotary catalysis mechanism. Isolated F1-ATPase catalytic cores can hydrolyze ATP, passing through six intermediate conformational states to generate rotation of their central subunit. Although previous structural studies have contributed greatly to understanding rotary catalysis in the F1-ATPase, the structure of an important conformational state (the binding-dwell) has remained elusive for 20 years. Here, we combine temperature and time-resolved cryo-electron microscopy to determine the structure of the binding- and catalytic-dwell states of Bacillus PS3 F1-ATPase. Each state shows three catalytic subunits in different conformations, establishing the complete set of six states taken up during the catalytic cycle and providing molecular details for both the ATP binding and hydrolysis strokes. We also identify a tunnel at the back of the catalytic site that indicates how ADP and phosphate binding are coordinated during synthesis. Overall these findings provide a structural basis for the entire F1-ATPase catalytic cycle.