title: Transient state kinetic analysis of the ATP-induced dissociation of the dynein-microtubule complex.
abstract: The kinetics of ATP-induced dissociation of dynein from the dynein-microtubule complex has been investigated by stopped flow light scattering methods. The addition of ATP to the dynein-microtubule complex induced a large, rapid decrease in light scattering followed by a smaller and much slower decrease. The fast light scattering change was shown to be a measure of the ATP-induced dissociation of dynein from the dynein-microtubule complex and was distinguished from microtubule disassembly by several criteria. (i) The fast reaction occurred over a period of milliseconds and the rate was a function of the ATP concentration, whereas, the slow reaction occurred over a period of several seconds and was independent of ATP concentration; (ii) the amplitude of the fast reaction was directly proportional to the amount of dynein bound to the microtubule lattice; and (iii) only the slow phase was inhibited by the addition of the microtubule-stabilizing drug, taxol. The rate of ATP-induced dissociation of dynein from the microtubule increased linearly with increasing ATP concentration to give an apparent second order rate constant for ATP binding equal to k1 = 4.7 X 10(6) M-1 s-1 according to the following pathway: (formula; see text) where M X D represents the dynein-microtubule complex and D represents dynein. The loss of signal amplitude at high ATP concentration provided a minimum estimate for the rate of dissociation of the ternary complex (M X D X ATP) equal to kd greater than 1000 s-1. Thus, the dynein-microtubule system is similar to actomyosin in that ATP induces an extremely rapid dissociation of dynein from the microtubule.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D004398:Dyneins / Q000378:metabolism*; D007700:Kinetics; D008027:Light; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism*; D017239:Paclitaxel; D012542:Scattering, Radiation; D013768:Tetrahymena / Q000201:enzymology*
chemical_list: D000470:Alkaloids; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D004398:Dyneins; D017239:Paclitaxel