Open AccessKinetics of force generation by single kinesin molecules activated by laser photolysis of caged ATP
Author(s) -
Hideo Higuchi,
Etsuko Muto,
Yuichi Inoue,
Toshio Yanagida
Publication year - 1997
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.94.9.4395
Subject(s) - kinesin , chemistry , atpase , photodissociation , kinetics , biophysics , flash photolysis , microtubule , laser , optical tweezers , reaction rate constant , photochemistry , enzyme , biochemistry , optics , biology , physics , microbiology and biotechnology , quantum mechanics
To relate transients of force by single kinesin molecules with the elementary steps of the ATPase cycle, we measured the time to force generation by kinesin after photorelease of ATP from caged ATP. Kinesin-coated beads were trapped by an infrared laser and brought onto microtubules fixed to a coverslip. Tension was applied to a kinesin-microtubule rigor complex using the optical trap, and ATP was released by flash photolysis of caged ATP with a UV laser. Kinesin started to generate force and move stepwise with a step size of 8 nm at average times of 31, 45, and 79 ms after photorelease of 450, 90, and 18 μM ATP, respectively. The kinetics of force generation were consistent with a two-step reaction: ATP binding, with an apparent second-order rate constant of 0.7 μM−1 ·s−1 , followed by force generation at 45 s−1 per kinesin molecule. The transient rate of force generation was close to the rate of the ATPase cycle in solution, suggesting that the rate-limiting step of ATPase cycle is involved with the force generation.