title: Dynein arms are strain-dependent direction-switching force generators.
abstract: Dynein is a minus-end-directed motor that can generate (forward) force to move along the microtubule toward its minus end. In addition, axonemal dyneins were reported to oscillate in the generation of forward force, and cytoplasmic dynein is observed to generate bidirectional forces in response to defined chemical states. Both dyneins can also respond to mechanically applied force. To test whether axonemal dynein can switch direction of force generation, we measured force using an optical trap and UV-photolysis of caged ATP. We observed that isolated dynein could repeatedly generate force in both directions along the microtubule. Bidirectional force was also observed for dynein arms that are still attached on the doublet microtubules. Axonemal dynein generated force to move backward (∼ 4 pN) as well as forward (5-6 pN) along microtubules. Furthermore, backward force could be stimulated by plus-end directed external force applied to axonemal dynein before ATP application. The results show that axonemal dynein is unique exhibiting multiple modes of force generation including backward and forward force, oscillatory force and slow, repetitive bidirectional force. The results also demonstrate that mechanical strain is important for switching the directionality of force generation in axonemal dyneins.
authors.affiliation: Department of Biological Sciences, The University of Tokyo, Hongo, Tokyo, Japan.
authors.forename: Chikako
authors.initials: C
authors.lastname: Shingyoji
authors.affiliation: Department of Biological Sciences, The University of Tokyo, Hongo, Tokyo, Japan.
authors.forename: Izumi
authors.initials: I
authors.lastname: Nakano
authors.affiliation: Department of Biological Sciences, The University of Tokyo, Hongo, Tokyo, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Inoue
authors.affiliation: Department of Physics, Graduate School of Science, The University of Tokyo, Hongo, Tokyo, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Higuchi
mesh_terms: D000818:Animals; D056444:Axonemal Dyneins / Q000378:metabolism*; D056445:Cytoplasmic Dyneins / Q000378:metabolism*; D004398:Dyneins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D009068:Movement; D012617:Sea Urchins / Q000378:metabolism*
chemical_list: D056444:Axonemal Dyneins; D056445:Cytoplasmic Dyneins; D004398:Dyneins
keywords: axonemal dynein; backward force; mechanical tension; sea urchin; sperm flagella