1: Proc Natl Acad Sci U S A  2000 Jun 20;97(13):7243-7 

Stepping rotation of F1-ATPase visualized through angle-resolved
single-fluorophore imaging.

Adachi K, Yasuda R, Noji H, Itoh H, Harada Y, Yoshida M, Kinosita K Jr.

Department of Physics, Faculty of Science, Kanazawa University, Kakuma-machi,
Kanazawa 920-1192, Japan.

Orientation dependence of single-fluorophore intensity was exploited in order to
videotape conformational changes in a protein machine in real time. The
fluorophore Cy3 attached to the central subunit of F(1)-ATPase revealed that the
subunit rotates in the molecule in discrete 120 degrees steps and that each step
is driven by the hydrolysis of one ATP molecule. These results, unlike those
from the previous study under a frictional load, show that the 120 degrees
stepping is a genuine property of this molecular motor. The data also show that
the rate of ATP binding is insensitive to the load exerted on the rotor subunit.

PMID: 10840052 [PubMed - indexed for MEDLINE]