COLLOQUIUM 2025

Abstract

F_oF₁-ATP synthase is one of the most ubiquitous and essential enzymes, driving ATP synthesis through oxidative phosphorylation. It is also a representative of a molecular rotary motor, which electrochemical energy stored in the proton motive force is converted into chemical free energy via mechanical rotation of an internal rotor. Since the direct observation of the rotary motion of the F_₁ catalytic domain, we have been exploring the mechanism of chemomechanical coupling in ATP synthase using single-molecule manipulation techniques and, more recently, structural analyses. These approaches have deepened our understanding of the fundamental principles governing its energy conversion mechanism.

In the first part of my talk, I will briefly summarize what we have learned about this rotary catalysis mechanism. In the later part, I will focus on fundamental questions regarding the design principles of this enzyme. For instance: why does the enzyme consistently adopt a structurally asymmetric configuration by attaching only one peripheral stalk, despite the intrinsic rotary symmetry of both F_₀ and F_₁? Why is symmetry mismatch between the two domains conserved across species? And what might the architecture of its ancestral form have looked like? Although these questions remain unresolved, I will present our recent findings based on protein engineering approaches, offering new perspectives on the evolutionary and functional logic that shapes this remarkable molecular machine.