Processive movement of single 22S dynein molecules occurs only at low ATP concentrations.
We have analyzed the movement of single 22S dynein molecules from Tetrahymena cilia by using a nanometer measuring system equipped with optical tweezers. Statistical analysis proved that a single molecule of 22S dynein can move processively and develop force at low concentrations of ATP (<20 microM). The maximum force was approximately 4.7 pN, and the force-velocity curve was convex down. During force development, dynein molecules showed stepwise displacement of approximately 8 nm and frequently exhibited backward steps of approximately 8 nm. At higher concentrations of ATP (>/=20 microM) single molecules of 22S dynein were not observed to move processively. Twenty-two S dynein seems to switch over from a processive mode to a nonprocessive mode, sensing a subtle change of ATP concentrations. These observations indicate that the processivity, maximum force, and step size of dynein are similar to those of kinesin, but the ATP concentration-dependence, force-velocity relationship, and backward steps are clearly distinct from kinesin.
Hirakawa
E
E
Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Tokyo 153-8902, Japan.
Higuchi
H
H
Toyoshima
Y Y
YY
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000378:metabolism; D002923:Cilia / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004398:Dyneins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D009068:Movement; D013552:Swine; D013768:Tetrahymena / Q000502:physiology; D013997:Time Factors
D000255:Adenosine Triphosphate; D004398:Dyneins