Temperature dependent properties of a kinesin-3 motor protein from Thermomyces lanuginosus

Kinesins are cytoskeletal motor proteins that share a common mechanochemical motor domain, and are responsible for trafficking macromolecules. Here we report the cloning and characterization of a monomeric, kinesin-3 (TKIN) from Thermomyces lanuginosus. TKIN displayed a maximum rate of ATP hydrolysis at ∼55 °C; the KmATP was also significantly greater at 50 °C. Gliding motility rates reached a maximum of 5.5 μm s−1 at 45 °C, which is among the highest rates reported for kinesin. Arrhenius energy barriers were calculated to be ∼103 kJ mol−1, nearly twofold greater than other mesophilic kinesin motors. The enthalpy of activation and entropy activation of TKIN were also significantly greater when compared to other mesophilic kinesins. A thermally induced aggregation of TKIN, which could be moderated by the addition of ATP, was observed at temperatures above 45 °C. Together, these results illustrate the kinetic response and stability of this unique motor protein at elevated temperatures.