Tubulin GTP hydrolysis influences the structure, mechanical properties, and kinesin-driven transport of microtubules.
Tubulin is a GTPase that hydrolyzes its bound nucleotide triphosphate after it becomes incorporated into a microtubule. The only known consequence of nucleotide hydrolysis is that it increases the dissociation rate of tubulin from the end of the microtubule by 2 orders of magnitude. In this study, we investigated whether microtubules composed of tubulin-GMPCPP (guanylyl alpha,beta-methylenediphosphate) (a very slowly hydrolyzed GTP analog) or tubulin-GDP exhibit additional structural or functional differences. We show that tubulin-GMPCPP microtubules are significantly stiffer than tubulin-GDP microtubules and have a 21% shallower protofilament twist angle. We also find that kinesin, a microtubule-based motor protein, transports tubulin-GMPCPP microtubules at approximately 30% faster rates than tubulin-GDP microtubules. These findings suggest that growing microtubule ends, which are thought to be composed of tubulin-GTP, may have different structural and mechanical properties from the remainder of the microtubule polymer.
Vale
R D
RD
Department of Pharmacology, University of California, San Francisco 94143.
Coppin
C M
CM
Malik
F
F
Kull
F J
FJ
Milligan
R A
RA
D000818:Animals; D001693:Biological Transport, Active; D002417:Cattle; D002465:Cell Movement; D049832:Decapodiformes; D004789:Enzyme Activation; D006150:Guanine Nucleotides / Q000378:metabolism*; D066298:In Vitro Techniques; D016547:Kinesins / Q000378:metabolism*; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D017239:Paclitaxel / Q000494:pharmacology; D014404:Tubulin / Q000378:metabolism*
D006150:Guanine Nucleotides; D014404:Tubulin; D016547:Kinesins; D017239:Paclitaxel