Kinesin is a microtubule-bound molecular motor that is involved in directed transport of organelles, cellular organization, mitosis, and signaling regulation. Using in vitro motility assays, structural studies and custom-built microscopes that can measure the force, steps, processivity, and velocity produced by single kinesin molecules, the Vale lab and our kinesin colleagues have built a model for kinesin motility. The key features of this model are highlighted in this movie from the 2000 Science review.
Kinesin is a dimeric motor protein that travels processively towards the microtubule plus end by taking 8 nm steps, which corresponds to the distance between adjacent alpha/beta tubulin binding sites. The coiled coil dimerization domain is shown in grey (the attached cargo would be at the end of the coiled coil, which is much longer than shown here). The Rice et al. paper proposed that a small peptide called the neck linker docks to the catalytic core in “ATP” states and undocks in “ADP” or nucleotide-free states. (The docked state is Yellow in the movie and undocked state is Red). When the rear head detaches (after phosphate release), then the neck linker docking in the front head pulls the detached partner head from a rear to a forward position. After a Brownian search (illustrated by the bouncing motion of the head), it binds to the forward tubulin binding site and this interaction causes ADP to be released. This microtubule binding event completes the 8 nm step and generates force. This cycle can then repeat as the kinesin takes many steps along the microtubule and the rear head can pass on either side of front head so as not to build up twist in the coiled coil. This asymmetric hand-over-hand motion is supported by studies from Yildiz et al. in conjunction with work from the Block and Hirose/Higuchi labs. The timing of events in this movie is not accurate, but intended to illustrate structural states in the cycle. Normally, the “step” (rearward detachment, translation past the partner head, diffusional search, and docking) would occur extremely rapidly and occupy a very small fraction of the ATPase cycle (see also studies by Carter and Cross).
(pdf) – Jonsson, E., Yamada, M., Vale, R.D., Goshima, G. (2015) Clustering of a kinesin-14 motor enables processive retrograde microtubule-based transport in plants. Nat Plants 1: 1-7. PMCID in process.
Recently, our lab has also found that unlike many of the plus-end directed kinesins, the minus-end kinesins in plants are not processive as dimers. However, upon clustering via either an artificial GCN motif or by recruitment onto liposomes, the motors are exhibit processive runs. This data suggests that the clustering of these kinesin-14 motors serves as a capable, dynein-independent mechanism for retrograde transport.
Using a combination of single-molecule spectroscopy, cryoelectron microscopy (with Ron Milligan’s group, Scripps Research Institute), pre-steady-state kinetics, and mutagenesis techniques, we identified a critical mechanical element in kinesin (called the neck linker) and showed that it undergoes nucleotide- and microtubule-dependent conformational changes.
(pdf) – Al-Bassam, J., Cui, Y., Klopfenstein, D., Carragher, B.O., Vale, R.D. and Milligan, R. A. (2003) Distinct conformations of the kinesin Unc104 neck regulate a monomer-to-dimer motor transition. J Cell Biol 163: 743-753.
(pdf) – Rice, S., Cui, Y., Sindelar, C., Naber, N., Matuska M., Vale, R. and Cooke R. (2003) Thermodynamic properties of the kinesin neck region docking to the catalytic core. Biophysical J 84:1844-1854.
(pdf) – Klopfenstein, D., Tomishige, M., Stuurman, N. and Vale, R.D. (2002) Role of Phosphatidylinositol(4,5)bisphosphate Organization in Membrane Transport by the Unc104 Kinesin Motor. Cell 109: 347-358.
(pdf) – Thorn, K.S., Ubersax, J.A., and Vale, R.D. (2000) Engineering the processive run length of the kinesin motor. J Cell Biol 151:1093-1100.
(pdf) – Vale, R.D., Milligan, R.A. (2000) The way things move: looking under the hood of molecular motor proteins. Science 288: 88-95.
(pdf) – Rice, S., Lin, A., W., Safer, D., Hart, C. L., Naber, N., Carragher, B. O., Cain, S. M., Pechatnikova, E., Wilson-Kubelek, E. M., Whitaker, M., Pate, E., Cooke R. , Taylor, E. W., Milligan, R. A., and Vale, R. D. (1999) A structural change in the kinesin motor protein that drives motility. Nature 402: 778-783.
(pdf) – Case, Ryan B., Pierce, Daniel W., Hom-Booher, Nora, Hart, Cynthia L. and Vale, Ronald D. (1997) The directional preference of kinesin motors is specified by an element outside of the motor catalytic domain. Cell 90: 959-966.
(pdf) – Sosa, Hernando, Dias, D. Prabha, Hoenger, Andreas, Whittaker, Michael, Wilson-Kubalek, Elizabeth, Sablin, Elena, Fletterick, R., Vale, Ronald D and Milligan, Ronald A. (1997) A model for the microtubule-Ncd motor protein complex obtained by cryo-electron microscopy and image analysis. Cell 90: 217-224.
(pdf) – Vale, Ronald D. and Fletterick, R. (1997) The design plan of kinesin motors. Annu Rev Cell Dev Biol 13: 745-77.
(pdf) – Kull, F. Jon, Sablin, Elena P., Lau, Rebecca, Fletterick, R. and Vale, Ronald D. (1996) Crystal structure of the kinesin motor domain reveals a structural similarity to myosin. Nature 380: 550-555.
(pdf) – Sablin, Elena P., Kull, F. Jon, Cooke R., Vale, Ronald D. and Fletterick, R. (1996) Crystal structure of the motor domain of the kinesin-related motor ncd. Nature 380: 555-559.
(pdf) – Vale, Ronald D. (1996) Switches, latches and amplifiers: common themes of G proteins and molecular motors (Commentary). J Cell Biol 135: 291-302.
(pdf) – Vale, Ronald D., Funatsu, Takashi, Pierce, Daniel W., Romberg, Laura, Harada, Yoshie and Yanagida, Toshio. (1996) Direct observation of single kinesin molecules moving along microtubules. Nature 380: 451-453.
(pdf) – Hoenger, A., Sablin, E.P., Vale, R.D., Fletterick, R., and Milligan, R.A. (1995) Three-dimensional structure of a tubulin-motor protein complex. Nature 376: 271-274.
Together with Robert Fletterick’s laboratory (University of California, San Francisco), we determined the atomic resolution structure of the kinesin motor domain and discovered unexpectedly that it is similar in structure to myosin, an actin-based motor.
(pdf) – Howard, J., Hudspeth, A.J. and Vale, R.D. (1989) Movement of microtubules by single kinesin molecules. Nature 342: 154-158.
(pdf) – Schnapp, B.J., Vale, R.D., Sheetz, M.P. and Reese, T.S. (1985) Single microtubules from squid axoplasm support bidirectional movement of organelles. Cell 40: 455-462.
(pdf) – Vale, R.D., Reese, T.S. and Sheetz, M.P. (1985) Identification of a novel force generating protein, kinesin, involved in microtubule-based motility. Cell 42: 39-50.
(pdf) – Vale, R.D., Schnapp, B.J., Mitchison, T., Steuer, E., Reese, T.S. and Sheetz, M.P. (1985) Different axoplasmic proteins generate movement in opposite directions along microtubules in vitro. Cell 43: 623-632.
(pdf) – Vale, R.D., Schnapp, B.J., Reese, T.S. and Sheetz, M.P. (1985) Organelle, bead and microtubule translocations promoted by soluble factors form the squid giant axon. Cell 40: 559-569.