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Tuning the mechanical stability of fibronectin type III modules through sequence variations.
David Craig1, Mu Gao, Klaus Schulten
1Department of Bioengineering, University of Washington, Seattle, WA 98195, USA.
Structure (London, England : 1993)
|January 17, 2004
Summary
Mechanical forces alter cell matrix protein function. We found that small sequence changes in fibronectin type III (FnIII) modules significantly impact their mechanical stability by controlling water interactions during unfolding.
Area of Science:
- Biophysics
- Molecular Biology
- Cellular Mechanics
Background:
- Cells modify extracellular matrix (ECM) protein function through mechanical forces.
- Fibronectin type III (FnIII) modules are key cell adhesion proteins within the ECM.
- FnIII modules exhibit low sequence homology but high cross-species conservation, indicating functional significance of sequence variations.
Purpose of the Study:
- To investigate how natural amino acid sequence variations affect the mechanical stability of fibronectin type III (FnIII) modules.
- To understand the molecular mechanisms by which sequence variations influence FnIII mechanical properties.
Main Methods:
- Steered molecular dynamics simulations were employed.
- Analysis focused on the impact of amino acid substitutions on the unfolding pathways of FnIII modules.
Main Results:
- Mechanical stability of FnIII modules can be tuned by altering a few key amino acids.
- Substitutions affect water molecule access to critical hydrogen bonds during early unfolding stages.
- Environmental factors (e.g., pH) and molecular interactions (e.g., heparin binding) can alter the mechanical unfolding hierarchy of specific FnIII modules (FnIII10, FnIII13).
Conclusions:
- Sequence variations in FnIII modules are functionally significant for mechanical stability.
- Water-mediated hydrogen bond dynamics are crucial for FnIII mechanical unfolding.
- Environmental and binding interactions provide additional layers of regulation for FnIII mechanical behavior.