The mode of ATP-dependent microtubule-kinesin sliding in the auxotonic condition.
Kinesin is a motor protein that converts chemical energy derived from ATP hydrolysis into mechanical work to transport cellular components along microtubules. We studied the properties of ATP-dependent microtubule-kinesin sliding with two different in vitro assay systems. In one assay system, a kinesin-coated glass microneedle (elastic coefficient, 1-2.5 pN microns -1) was made to slide along an axoneme. Using this system, we obtained the relationship between the force (= load) on the microneedle and the velocity of microneedle-kinesin sliding in the auxotonic condition, in which the load on the microtubule-kinesin contacts increased as sliding progressed. The force-velocity curve was upwardly convex (maximum velocity Vmax, 0.58 +/- 0.15 microns s-1; maximum isometric force P0, 5.0 +/- 1.6 pN) and was similar to that of in vitro actin-myosin sliding in the auxotonic condition, suggesting that the two motor protein systems have fundamental kinetic properties in common. In the other assay system, an axoneme attached to a glass microneedle (elastic coefficient, 4-5 pN microns -1) was made to slide on a kinesin-coated glass surface (Vmax, 0.68 +/- 0.17 microns s-1; P0, 46.1 +/- 18.6 pN). The change in shape of the axoneme indicated an enormous flexibility of randomly oriented kinesin molecules.
Shirakawa
I
I
Department of Physiology, School of Medicine, Teikyo University, Tokyo, Japan.
Oiwa
K
K
Chaen
S
S
Shimizu
T
T
Tanaka
H
H
Sugi
H
H
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002417:Cattle; D005898:Glass; D016547:Kinesins / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008870:Microtubules / Q000378:metabolism*; D009339:Needles; D012617:Sea Urchins; D013094:Spermatozoa / Q000648:ultrastructure
D000255:Adenosine Triphosphate; D016547:Kinesins