Thermal activation energy for bidirectional movement of actin along bipolar tracks of myosin filaments

Previous in vitro motility assays using bipolar myosin thick filaments demonstrated that actin filaments were capable of moving in both directions along the myosin filament tracks. The movements; however, were slower in the direction leading away from the central bare zone than towards it. To unders...

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Bibliographic Details
Published in:Biochemical and biophysical research communications 2010-05, Vol.396 (2), p.539-542
Main Authors: Okubo, Hiroyuki, Iwai, Masanori, Iwai, Sosuke, Chaen, Shigeru
Format: Article
Language:English
Subjects:
Actins - chemistry
Actins - physiology
Adenosine Triphosphate - chemistry
Adenosine Triphosphate - physiology
ADP release
Brownian motion
Hot Temperature
In vitro motility assay
Movement
Myosins - chemistry
Myosins - physiology
Thermal fluctuation
Thick filament
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Summary:Previous in vitro motility assays using bipolar myosin thick filaments demonstrated that actin filaments were capable of moving in both directions along the myosin filament tracks. The movements; however, were slower in the direction leading away from the central bare zone than towards it. To understand the mechanism underlying these different direction-dependent motilities, we have examined the effects of temperature on the velocities of the bidirectional movements along reconstituted myosin filaments. Activation energies of the movements were determined by Arrhenius plots at high and low concentrations of ATP. As a result, the thermal activation energy of the movement away from the central bare zone was significantly higher than that of the movement toward the zone. Given that the backward movement away from the central bare zone would cause the myosin heads to be constrained and the stiffness of the cross-bridges to increase, these results suggest that elastic energy required for the cross-bridge transition is supplied by thermal fluctuations.
ISSN:0006-291X
1090-2104
DOI:10.1016/j.bbrc.2010.04.139