Force-induced bidirectional stepping of cytoplasmic dynein.
Cytoplasmic dynein is a minus-end-directed microtubule motor whose mechanism of movement remains poorly understood. Here, we use optical tweezers to examine the force-dependent stepping behavior of yeast cytoplasmic dynein. We find that dynein primarily advances in 8 nm increments but takes other sized steps (4-24 nm) as well. An opposing force induces more frequent backward stepping by dynein, and the motor walks backward toward the microtubule plus end at loads above its stall force of 7 pN. Remarkably, in the absence of ATP, dynein steps processively along microtubules under an external load, with less force required for minus-end- than for plus-end-directed movement. This nucleotide-independent walking reveals that force alone can drive repetitive microtubule detachment-attachment cycles of dynein's motor domains. These results suggest a model for how dynein's two motor domains coordinate their activities during normal processive motility and provide new clues for understanding dynein-based motility in living cells.
The Howard Hughes Medical Institute and the Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, CA 94158-2200, USA.
Arne
A
Gennerich
Andrew P
AP
Carter
Samara L
SL
Reck-Peterson
Ronald D
RD
Vale
D000255:Adenosine Triphosphate / Q000378:metabolism; D001693:Biological Transport, Active; D001696:Biomechanical Phenomena; D003593:Cytoplasm / Q000378:metabolism; D004398:Dyneins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D006868:Hydrolysis; D008954:Models, Biological; D017434:Protein Structure, Tertiary / Q000502:physiology; D012441:Saccharomyces cerevisiae
D000255:Adenosine Triphosphate; D004398:Dyneins