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Mechanically induced titin kinase activation studied by force-probe molecular dynamics simulations
Frauke Gräter1, Jianhua Shen, Hualiang Jiang
1Theoretical and Computational Biophysics Department, Max-Planck-Institute for Biophysical Chemistry, 37077 Göttingen, Germany.
Biophysical Journal
|November 9, 2004
Summary
Titin kinase, a protein in muscle cells, acts as a force sensor by mechanically opening its active site through sequential beta-sheet rupture, without full unfolding. This supports its role in converting mechanical stress into biochemical signals.
Area of Science:
- Biophysics
- Molecular Biology
- Muscle Physiology
Background:
- Muscle cells convert mechanical stress into biochemical signals via force sensors.
- Titin kinase, part of the elastic protein titin, is a proposed candidate for this force-sensing role.
- Activation of titin kinase involves significant conformational changes and active site exposure.
Purpose of the Study:
- To investigate the tension-induced activation mechanism of titin kinase.
- To understand how mechanical stress leads to the activation of titin kinase.
Main Methods:
- Force-probe molecular dynamics simulations were employed.
- Analysis of mechanically induced conformational changes and domain unfolding.
Main Results:
- Evidence for sequential, mechanically induced opening of the catalytic site.
- Identified rupture of two terminal beta-sheets as key initial unfolding steps.
- Observed rearrangement of the autoinhibitory tail leading to active site exposure.
Conclusions:
- Titin kinase activation occurs via partial unfolding, specifically beta-sheet rupture.
- Differences in beta-sheet geometry explain varying force resistance.
- Findings support titin kinase's function as a molecular force sensor in muscle.