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Myomesin is a molecular spring with adaptable elasticity
Roman Schoenauer1, Patricia Bertoncini, Gia Machaidze
1Institute of Cell Biology, ETH Zürich-Hönggerberg, CH-8093 Zürich, Switzerland.
Journal of Molecular Biology
|May 14, 2005
Summary
Myomesin, a key M-band protein, acts as a molecular spring. Its unique EH-segment provides elasticity, contributing to sarcomere stability.
Area of Science:
- Muscle structure and function
- Biophysics
- Molecular biology
Background:
- The M-band stabilizes the sarcomere's thick filament lattice.
- Myomesin, a constitutive M-band protein, forms dimers that may cross-link thick filaments.
- The EH-myomesin splice isoform includes a unique EH-segment.
Purpose of the Study:
- To biophysically characterize myomesin and its EH-segment.
- To investigate the mechanical properties of myomesin's domains and splice variants.
- To understand myomesin's role in sarcomere stability.
Main Methods:
- Atomic force microscopy (AFM) for mechanical fingerprinting.
- Transmission electron microscopy (TEM) for structural visualization.
- Circular dichroism (CD) spectroscopy for conformational analysis.
Main Results:
- Immunoglobulin-like (Ig) and fibronectin type III (Fn) domains exhibit reversible unfolding.
- The EH-segment behaves as an entropic chain with a random coil conformation.
- Myomesin functions as a molecular spring with elasticity modulated by splicing.
Conclusions:
- Myomesin's viscoelastic properties, including its spring-like EH-segment, are crucial for sarcomere stability.
- Alternative splicing modulates myomesin's elasticity.
- Ig and Fn domains may act as shock absorbers under high mechanical stress.