The Power Stroke Distance of Human Cytoplasmic Dynein

Abstract

Cytoplasmic dynein is a motor protein moving along microtubules, and plays important roles in vesicle transport and mitosis. To understand the molecular mechanism of dynein motility, we measured the efficiency of FRET from dynein ring-BFP to linker-GFP, and the displacement driven by single-headed dynein interacting with microtubules by optical tweezers. The efficiency and the apparent stroke displacement depend on ATP concentration. The low efficiency and displacement at low ATP concentration indicate no conformational change of dynein at no ATP binding (apo) state that is predominant at low ATP concentration. With increasing ATP concentration, population of apo state decreases and that of the pre-power stroke state such as dynein ADP-Pi should increase. Dynein at the pre-power stroke state will generate the power stroke at binding to microtubule. Therefore, the displacement increased with ATP concentration. This is the first obtained interesting result and has not been reported for myosin and kinesin power strokes. High FRET efficiency and distance (8-9 nm) at saturated concentration of ATP indicate that the 8-9 nm power stroke distance is generated by swing of linker. This is supported by the result that the dynein deleted at the loops interacted with the linker did not generate the power stroke. The power stroke driven by the conformational change of dynein linker will be the fundamental mechanism of dynein motility.