F1-ATPase is a rotary motor enzyme in which a single ATP molecule drives a 120° rotation of the central γ subunit relative to the surrounding α3β3 ring. Here, we show that the rotation of F1-ATPase spontaneously lapses into long (≅30 s) pauses during steady-state catalysis. The effects of ADP-Mg and mutation on the pauses, as well as kinetic comparison with bulk-phase catalysis, strongly indicate that the paused enzyme corresponds to the inactive state of F1-ATPase previously known as the ADP-Mg inhibited form in which F1-ATPase fails to release ADP-Mg from catalytic sites. The pausing position of the γ subunit deviates from the ATP-waiting position and is most likely the recently found intermediate 90° position.
|Number of pages
|Proceedings of the National Academy of Sciences of the United States of America
|Published - 2001 Nov 20
ASJC Scopus subject areas