Enhanced stability of kinesin-1 as a function of temperature

Kinesin-1 is a mechanochemical enzyme which mediates long distance intracellular cargo transport along microtubules in a wide variety of eukaryotic cells. Kinesin is also relatively easy to purify and shows robust function in vitro, leading to numerous proposals for using the kinesin-1/microtubule system for nanoscale transport in engineered devices. However, kinesin in vitro shows signs of degradation at ∼30 °C which severely limits its usability in biomimetic engineering. Notably, kinesin-1 functions robustly in animal cells at body temperatures as high as 40 °C which suggests that kinesin functioning can be stabilized beyond what is observed in vitro. The present study investigated the effect of trimethylamine N-oxide (TMAO) as a potential heat-protecting agent for kinesin function and microtubule stability. We show that at a concentration of 200 mM, TMAO can indeed stabilize kinesin-based motility up to a little over 50 °C and that such motility can be sustained for extended periods of time. Our results suggest that intracellular crowding (mimicked in vitro by TMAO) can indeed stabilize kinesin-1 at high temperatures and helps resolve a long standing discrepancy between thermal stability of kinesin-1 observed in vivo and in vitro. Moreover, when considered together with our previous report that kinesin-1 can function well down to near-freezing conditions, this study establishes kinesin-1/microtubule motility as a thermally viable engineering platform.