title: Torque generation by axonemal outer-arm dynein.
abstract: Outer-arm dynein is the main engine providing the motive force in cilia. Using three-dimensional tracking microscopy, we found that contrary to previous reports Tetrahymena ciliary three-headed outer-arm dynein (αβγ) as well as proteolytically generated two-headed (βγ) and one-headed (α) subparticles showed clockwise rotation of each sliding microtubule around its longitudinal axis in microtubule corkscrewing assays. By measuring the rotational pitch as a function of ATP concentration, we also found that the microtubule corkscrewing pitch is independent of ATP concentration, except at low ATP concentrations where the pitch generated by both three-headed αβγ and one-headed α exhibited significantly longer pitch. In contrast, the pitch driven by two-headed βγ did not display this sensitivity. In the assays on lawns containing mixtures of α and βγ at various ratios, the corkscrewing pitch increased dramatically in a nonlinear fashion as the ratio of α in the mixture increased. Even small proportions of α-subparticle could significantly increase the corkscrewing pitch of the mixture. Our data show that torque generation does not require the three-headed outer-arm dynein (αβγ) but is an intrinsic property of the subparticles of axonemal dyneins and also suggest that each subparticle may have distinct mechanical properties.
authors.affiliation: Department of Life Sciences, Graduate School of Arts & Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Shin
authors.initials: S
authors.lastname: Yamaguchi
authors.affiliation: Department of Life Sciences, Graduate School of Arts & Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Saito
authors.affiliation: Department of Life Sciences, Graduate School of Arts & Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Miki
authors.initials: M
authors.lastname: Sutoh
authors.affiliation: Department of Physics, Gakushuin University, Tokyo, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Nishizaka
authors.affiliation: Department of Life Sciences, Graduate School of Arts & Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Yoko Y
authors.initials: YY
authors.lastname: Toyoshima
authors.affiliation: Department of Life Sciences, Graduate School of Arts & Sciences, The University of Tokyo, Tokyo, Japan. Electronic address: yajima@bio.c.u-tokyo.ac.jp.
authors.forename: Junichiro
authors.initials: J
authors.lastname: Yajima
mesh_terms: D056444:Axonemal Dyneins / Q000737:chemistry*; D015800:Protozoan Proteins / Q000737:chemistry*; D013768:Tetrahymena / Q000737:chemistry / Q000378:metabolism; D019415:Torque
chemical_list: D015800:Protozoan Proteins; D056444:Axonemal Dyneins