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- Title
Processivity of the single-headed kinesin KIF1A through biased binding to tubulin.
- Authors
Okada, Yasushi; Higuchi, Hideo; Hirokawa, Nobutaka
- Abstract
Conventional isoforms of the motor protein kinesin behave functionally not as 'single molecules' but as 'two molecules' paired. This dimeric structure poses a barrier to solving its mechanism[SUP1-4]. To overcome this problem, we used an unconventional kinesin KIF1A (refs 5, 6) as a model molecule. KIF1A moves processively as an independent monomer[SUP7,8], and can also work synergistically as a functional dimmer[SUP9]. Here we show, by measuring its movement with an optical trapping system[SUP10], that a single ATP hydrolysis triggers a single stepping movement of a single KIF1A monomer. The step size is distributed stochastically around multiples of 8 nm with a gaussian-like envelope and a standard deviation of 15 nm. On average, the step is directional to the microtubule's plus-end against a load force of up to 0.15 pN. As the source for this directional movement, we show that KIF1A moves to the microtubule's plus-end by, ∼ 3 nm on average on binding to the microtubule, presumably by preferential binding to tubulin on the plus-end side. We propose a simple physical formulation to explain the movement of KIF1A.
- Subjects
KINESIN; TUBULINS; MICROTUBULES; PROTEIN binding; DIMERS
- Publication
Nature, 2003, Vol 424, Issue 6948, p574
- ISSN
0028-0836
- Publication type
Article
- DOI
10.1038/nature01804