Kinesin Walks Hand-Over-Hand

  title={Kinesin Walks Hand-Over-Hand},
  author={Ahmet Yildiz and Michio Tomishige and Ronald D. Vale and Paul R. Selvin},
  pages={676 - 678}
Kinesin is a processive motor that takes 8.3-nm center-of-mass steps along microtubules for each adenosine triphosphate hydrolyzed. Whether kinesin moves by a “hand-over-hand” or an “inchworm” model has been controversial. We have labeled a single head of the kinesin dimer with a Cy3 fluorophore and localized the position of the dye to within 2 nm before and after a step. We observed that single kinesin heads take steps of 17.3 ± 3.3 nm. A kinetic analysis of the dwell times between steps shows… 

How kinesin waits between steps

Two different single-molecule fluorescence resonance energy transfer (smFRET) sensors are developed to detect whether kinesin is bound to its microtubule track by one or two heads and suggest a model for how transitions in the ATPase cycle position the two kinesIn heads and drive their hand-over-hand motion.

Kinesin's step dissected with single-motor FRET

FRET is used to resolve the relative distance between the motor domains and their relative orientation, on the submillisecond timescale, during processive stepping and reveals that, during a step, a kinesin motor domain dwells in a well-defined intermediate position for ≈3 ms.

Direct observation of intermediate states during the stepping motion of kinesin-1.

High-temporal resolution dark-field microscopy was employed to directly visualize the binding and unbinding of kinesin heads to or from microtubules during processive movement, thereby explaining how the two heads coordinate to move in a hand-over-hand manner.

Examining kinesin processivity within a general gating framework

Kinesin-1 is primarily front-head gated, and that NL length is tuned to enhance unidirectional processivity and velocity, and cysteine-light mutants do not produce wild-type motility under load.

Kinesin steps do not alternate in size.

By analyzing single-molecule stepping traces from "limping" kinesin molecules, it is able to distinguish alternate fast- and slow-phase steps and thereby to calculate the step sizes associated with the motions of each of the two heads.

Coordination between Motor Domains in Processive Kinesins*

The phenomenon of kinesin processivity is reviewed from a complementary perspective by considering specific structural features of the motor domains that underlie their coordination, and how these features contribute to its processive movement.

Understanding Kinesin's Gating Mechanism by Optical Trap

The results suggest that geometrical constraints of the neck linker domains in a walking kinesin dimer break the symmetry of the two identical heads, such that the trailing head is free to move when the leading head is unable to bind nucleotide.

Direct observation of the binding state of the kinesin head to the microtubule

A single-molecule assay is reported that can directly report head binding in a walking kinesin molecule, and it is shown that only a single head is bound to the microtubule between steps at low ATP concentrations.

Kinesin's moonwalk.




Distinguishing Inchworm and Hand-Over-Hand Processive Kinesin Movement by Neck Rotation Measurements

There were no rotations in the kinesin stepping mechanism, a finding that is inconsistent with symmetric hand-over-hand movement, and an alternative “inchworm” mechanism is consistent with the experimental results.

Nucleotide-dependent single- to double-headed binding of kinesin.

Kinesin binds through two heads in the former and one head in the latter two states of adenosine 5'-diphosphate hydrolysis, which supports a major prediction of the hand-over-hand model.

Myosin V Walks Hand-Over-Hand: Single Fluorophore Imaging with 1.5-nm Localization

The results strongly support a hand-over-hand model of motility, not an inchworm model, which moves processively on actin.

Stepping and Stretching

The data argue that the major effect of the internal strain generated when both motor domains of kinesin bind the microtubule is to block ATP from binding to the leading motor, guaranteeing the two motor domains remain out of phase for many mechanochemical cycles and provides an efficient and adaptable mechanism for the maintenance of processive movement.

Probing the kinesin reaction cycle with a 2D optical force clamp

Sideways loads slow the kinesin motor asymmetrically, but only at higher ATP levels, revealing the presence of additional, load-dependent transitions late in the cycle, and confirming that hydrolysis remains tightly coupled to stepping.

Configuration of the two kinesin motor domains during ATP hydrolysis

The relative configuration of the two kinesin motor domains during ATP hydrolysis is investigated using fluorescence polarization microscopy of ensemble and single molecules and it is proposed that the motor neck-linker domain configuration controls ADP release.

A structural change in the kinesin motor protein that drives motility

A large conformational change of a ∼15-amino-acid region (the neck linker) in kinesin is detected and visualized using electron paramagnetic resonance, fluorescence resonance energy transfer, pre-steady state kinetics and cryo-electron microscopy.

The road less traveled: emerging principles of kinesin motor utilization.

The rapid expansion in the understanding of how eukaryotic cells take advantage of kinesin superfamily proteins to generate force and movement in diverse functional contexts is discussed.

A new look at the microtubule binding patterns of dimeric kinesins.

This work reinvestigated the microtubule binding patterns of dimeric kinesins by cryo-EM and digital 3D reconstruction under different nucleotide conditions and different motor:tubulin ratios, and determined the molecular mass of motor-tubulin complexes by STEM.