Thermal activation of single kinesin molecules with temperature pulse microscopy

Conventional kinesin is a processive motor protein that keeps "walking" along a microtubule using chemical energy released by ATP hydrolysis. We previously studied the effects of temperature between 15° and 35°C on the moving velocity, force, and processivity of single kinesin molecules using a bead assay [Kawaguchi and Ishiwata, 2000b: Biochem Biophys Res Commun 272:895-899]. However, we could not examine the effects of temperature higher than 35°C because of the thermal damage to proteins. Here, using temperature pulse microscopy (TPM) [Karo et al., 1999: Proc Natl Acad Sci USA 96:9602-9606], we could examine the temperature dependence of the gliding velocity of single kinesin molecules interacting with a microtubule above 35°C up to 50°C (instantaneously, ∼60°C), where the velocity reached 3.68 μm/s, the highest ever reported. The Arrhenius plot showed no breaks between 15° and 50°C with a unique activation energy of about 50 kJ/mol, suggesting that the molecular mechanism of kinesin motility is common over a broad temperature range including physiological temperature.