Frontiers in ATP synthase research: understanding the relationship between subunit movements and ATP synthesis.

How biological systems make ATP has intrigued many scientists for well over half the 20th century, and because of the importance and complexity of the problem it seems likely to continue to be a source of fascination to both senior and younger investigators well into the 21st century. Scientific battles fought to unravel the vast secrets by which ATP synthases work have been fierce, and great victories have been short-lived, tempered with the realization that more structures are needed, additional subunits remain to be conquered, and that during ATP synthesis, not one, but several subunits may undergo either significant conformational changes, repositioning, or perhaps even physical "rotation" similar to bacterial flagella (1,2). In this introductory article, the author briefly summarizes our current knowledge about the complex substructure of ATP synthases, what we have learned from X-ray crystallography of the F1 unit, and current evidence for subunit movements.