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Human cardiac myosin binding protein C: structural flexibility within an extended modular architecture
Cy M Jeffries1, Yanling Lu, Robert M G Hynson
1School of Molecular Bioscience, University of Sydney, New South Wales 2006, Australia.
Journal of Molecular Biology
|November 2, 2011
Summary
Human cardiac myosin binding protein C (cMyBP-C) has a flexible, extended N-terminus, revealing its modular organization. This structure may enable cMyBP-C to act as a molecular switch in heart muscle contraction.
Area of Science:
- Biochemistry
- Structural Biology
- Muscle Physiology
Background:
- Cardiac myosin binding protein C (cMyBP-C) is crucial for cardiac muscle structure and function.
- Understanding its modular organization and flexibility is key to elucidating its role in muscle contraction.
Purpose of the Study:
- To investigate the structural organization and flexibility of human cMyBP-C.
- To determine the association state of full-length cMyBP-C.
Main Methods:
- Combined small-angle X-ray scattering (SAXS) and Nuclear Magnetic Resonance (NMR) spectroscopy.
- Analysis of domain fragments and full-length cMyBP-C.
Main Results:
- The N-terminal half of cMyBP-C exhibits a flexible, extended, and 'bent' modular arrangement, similar to titin.
- A proline/alanine-rich linker provides flexibility at the N-terminus, while domains C1-C4 are more rigid.
- Full-length cMyBP-C forms flexible extended dimers in solution.
Conclusions:
- Human cMyBP-C possesses a unique modular architecture with significant flexibility, particularly in its N-terminal region.
- These structural features suggest a role as a molecular switch and in modulating muscle elasticity.
- The extended N-terminus can accommodate interfilament spacing changes in heart muscle.
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