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Solution structure of heavy meromyosin by small-angle scattering.
Samantha P Harris1, William T Heller, Marion L Greaser
1Department of Physiology, University of Wisconsin Medical School, Madison, Wisconsin 53706, USA. spharris@physiology.wisc.edu
The Journal of Biological Chemistry
|December 6, 2002
Summary
Researchers studied the shape of double-headed myosin using scattering techniques. They found myosin heads are not symmetrical and one head bends back, revealing new insights into myosin structure and function.
Area of Science:
- Biochemistry
- Structural Biology
- Biophysics
Background:
- X-ray crystallography revealed atomic details of myosin S1 subfragments, including nucleotide and actin binding sites.
- This advanced understanding of force generation coupled to ATP hydrolysis.
- The 3D structure of double-headed myosin (two S1 subfragments) remained unsolved.
Purpose of the Study:
- To investigate the overall shape and relative orientations of the two myosin heads.
- To explore the structure of the head-tail junction in solution.
Main Methods:
- Small-angle X-ray scattering (SAXS) measurements.
- Small-angle neutron scattering (SANS) measurements.
- Heavy meromyosin (containing all three light chains, LC(1-3)) in solution was used.
Main Results:
- Scattering intensity profiles were best fit by models with an angular separation between heads less than 180 degrees.
- The S1 heads are not related by an axis of symmetry.
- One S1 head was modeled as bent back along the rod.
Conclusions:
- New information on the structure of the myosin head-tail junction was obtained.
- Combining scattering measurements with structural modeling is a viable method for studying myosin head-head interactions in solution.