The principal motions involved in the coupling mechanism of the recovery stroke of the myosin motor
- University of Heidelberg
- ORNL
Muscle contraction is driven by a cycle of conformational changes in the myosin II head. After myosin binds ATP and releases from the actin fibril, myosin prepares for the next power stroke by rotating back the converter domain that carries the lever arm by {approx}60 degrees. This recovery stroke is coupled to the activation of myosin's ATPase by a mechanism that is essential for an efficient motor cycle. The mechanics of this coupling have been proposed to occur via two distinct and successive motions of the two helices that hold the converter domain: in a first phase a see-saw motion of the relay helix, followed by a piston/seesaw motion of the SH1 helix in a second phase. To test this model, we have determined the principal motions of these structural elements during equilibrium molecular dynamics simulations of the crystallographic end states of the recovery stroke by using Principal Component Analysis. This reveals that the only principal motions of these two helices that make a large amplitude contribution towards the conformational change of the recovery stroke are indeed the predicted seesaw and piston motions.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Laboratory Directed Research and Development (LDRD) Program
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 950441
- Journal Information:
- Journal of Molecular Biology, Vol. 367, Issue 2; ISSN 0022-2836
- Country of Publication:
- United States
- Language:
- English
Similar Records
The structural coupling between ATPase activation and recovery stroke in the myosin II motor
Electron Tomography of Cryofixed, Isometrically Contracting Insect Flight Muscle Reveals Novel Actin-Myosin Interactions