Structural basis of unisite catalysis of bacterial F0F1-ATPase

Adenosine triphosphate (ATP) synthases (F0F1-ATPases) are crucial for all aerobic organisms. F-1, a water-soluble domain, can catalyze both the synthesis and hydrolysis of ATP with the rotation of the central gamma epsilon rotor inside a cylinder made of alpha(3)beta(3) in three different conformations (referred to as beta(E), beta(TP), and beta(DP)). In this study, we determined multiple cryo-electron microscopy structures of bacterial F0F1 exposed to different reaction conditions. The structures of nucleotide-depleted F0F1 indicate that the epsilon subunit directly forces beta(TP) to adopt a closed form independent of the nucleotide binding to beta(TP). The structure of F0F1 under conditions that permit only a single catalytic beta subunit per enzyme to bind ATP is referred to as unisite catalysis and reveals that ATP hydrolysis unexpectedly occurs on beta(TP) instead of beta(DP), where ATP hydrolysis proceeds in the steady-state catalysis of F0F1. This indicates that the unisite catalysis of bacterial F0F1 significantly differs from the kinetics of steady-state turnover with continuous rotation of the shaft.

Automated summary

Adenosine triphosphate (ATP) synthases are crucial for all aerobic organisms. This study determined the cryo-electron microscopy structures of bacterial F0F1 under different reaction conditions and revealed that the unisite catalysis of bacterial F0F1 significantly differs from the kinetics of steady-state turnover.