Molecular motors: Stretching the lever-arm theory

  title={Molecular motors: Stretching the lever-arm theory},
  author={Michael A. Geeves},
  • M. Geeves
  • Published 10 January 2002
  • Biology
  • Nature
Motor proteins are essential to life: without them, all cellular transport would grind to a halt. New results on the size of steps taken by one family of motors, the myosins, will fuel the debate about how they move. 

A new model for myosin dimeric motors incorporating Brownian ratchet and powerstroke mechanisms

A new dimer model is introduced to describe the behavior of dimeric processive motor proteins in general and the results are compared with experimental data for two-headed processive motors.

Power-Stroke-Driven Muscle Contraction

To show that acto-myosin contraction can be propelled directly through a conformational change, we present in these lecture notes a review of a recently developed approach to muscle contraction where

An electromechanical model of myosin molecular motors.

  • T. Masuda
  • Biology
    Journal of theoretical biology
  • 2003

Conformational change of the actomyosin complex drives the multiple stepping movement

A theoretical model in which the refolding of the partially unfolded actomyosin complex and the movement of the myosin head along the actin filament are coupled is proposed, which quantitatively explains the single-molecular observation of the multiple stepping movement and is consistent with structural observations of the disorder in the actomyOSin-binding process.

Molecular dynamics simulation for the reversed power stroke motion of a myosin subfragment-1




Myosin motors with artificial lever arms.

Replacement of the LCBD with genetically engineered domains of similar rigidity and dimensions produces functional molecular motors with unchanged kinetic properties, ideal models for the investigation of chemo‐mechanical coupling in the myosin motor.

Two-headed binding of a processive myosin to F-actin

Myosins are motor proteins in cells. They move along actin by changing shape after making stereospecific interactions with the actin subunits. As these are arranged helically, a succession of steps

Myosin VI is a processive motor with a large step size

Here it is shown that myosin VI is also processive by using single molecule motility and optical trapping experiments, and takes much larger steps than expected, based on a simple lever-arm mechanism, for aMyosin with only one light chain in the lever- arm domain.

Myosin VI is an actin-based motor that moves backwards

Myosin VI achieves reverse-direction movement by rotating its lever arm in the opposite direction to conventional myosin lever arm movement, and is visualized using cryo-electron microscopy and image analysis.

The neck region of the myosin motor domain acts as a lever arm to generate movement.

A mutant with a longer neck moves faster than the wild type, and the sliding velocities of these myosins are linearly related to the neck length, as predicted by the swinging neck-lever model.

Single-molecule tracking of myosins with genetically engineered amplifier domains

The engineered change in the step size of myosin marks a significant advance in the ability to selectively modify the functional properties of molecular motors.

Myosin V exhibits a high duty cycle and large unitary displacement

The laser trap and in vitro motility assay was used to characterize the mechanics of heavy meromyosin–like fragments of myosin V (M5HMM) expressed in the Baculovirus system and suggested a high duty cycle would allow actin filament translocation and thus organelle transport by a few M5H MM molecules.

The gated gait of the processive molecular motor, myosin V

The mechanical interactions between mouse brain myosin V and rabbit skeletal F-actin are measured and it is proposed that the 36-nm steps of the double-headed motor are a combination of the working stroke of the bound head and a biased, thermally driven diffusive movement of the free head onto the next target zone.

The motor domain determines the large step of myosin-V

The mechanical properties of single molecules of myosin-V truncation mutants with neck domains only one-sixth of the native length are measured and show that the processivity and step distance along actin are both similar to those of full-length myosIn-V.

Structural mechanism of muscle contraction.

Cryoelectronmicroscopy has revealed other angles of the cross-bridge lever arm induced by ADP binding and these structural states are presently being characterized by site-directed mutagenesis coupled with kinetic analysis.