Fluctuations are ubiquitous and prominent in microscopic systems. Observations in vitro have confirmed motor proteins are subjected to thermal fluctuations. The walking molecular motor, kinesin-1 (hereafter called kinesin), which carries vesicles on microtubules in cells, has long been proposed to utilize thermal fluctuations to make directed movements. In addition to thermal fluctuations, living cells actively generate non-thermal fluctuations using energy derived from metabolic activities. However, it is not clear whether and how these active fluctuations affect the function of kinesins in living cells. To investigate the effect of active fluctuations on single kinesin molecules , we used an in vitro measurement system to apply actively fluctuating external forces (i.e. noise), artificially mimicking intracellular active fluctuations. Here we show that kinesin accelerates in response to the applied noise, especially under the application of a large average hindering force (load ). The acceleration was quantitatively explained with a mathematical model using independently determined parameters . The universality of the theory behind the model suggests that intracellular enzymes share a similar noise-induced acceleration mechanism, meaning that the active fluctuations in cells are not just noise but utilized to improve the activity of biomolecules .
The movement of single kinesin molecules was observed while applying noisy external forces that mimic intracellular active fluctuations. We found kinesin accelerates under noise, especially when a large hindering load is added. The behavior quantitatively conformed to a theoretical model that describes the kinesin movement with simple two-state reactions . The universality of the kinetic theory suggests that intracellular enzymes share a similar noise-induced acceleration mechanism, i.e. active fluctuations in cells are not just noise but are utilized to promote various physiological processes .
R
Fluctuations are ubiquitous and prominent in microscopic systems. Observations in vitro have confirmed motor proteins are subjected to thermal fluctuations. The walking molecular motor, kinesin-1 (hereafter called kinesin), which carries vesicles on microtubules in cells, has long been proposed to utilize thermal fluctuations to make directed movements. In addition to thermal fluctuations, living cells actively generate non-thermal fluctuations using energy derived from metabolic activities. However, it is not clear whether and how these active fluctuations affect the function of kinesins in living cells. To investigate the effect of active fluctuations on
The movement of
R
, we used an in vitro measurement system to apply actively fluctuating external forces (i.e. noise), artificially mimicking
was observed while applying noisy external forces that mimic
R
Here we show that kinesin accelerates in response to the applied
We found kinesin accelerates under
R
under the application of a large average hindering force (load ). The acceleration was quantitatively explained with a mathematical model using independently determined parameters
when a large hindering load is added. The behavior quantitatively conformed to a theoretical model that describes the kinesin movement with simple two-state reactions
R
theory behind the model
kinetic theory
R
meaning that the
i.e.
R
utilized to improve the activity of biomolecules
are utilized to promote various physiological processes