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Curvature variation along the tropomyosin molecule
Xiaochuan Edward Li1, William Lehman, Stefan Fischer
1Department of Physiology and Biophysics, Boston University School of Medicine, 72 East Concord Street, Boston, MA 02118, USA; Computational Biochemistry Group, University of Heidelberg, Im Neuenheimer Feld 368, Heidelberg D-69120, Germany.
Journal of Structural Biology
|December 23, 2009
Summary
Alanine clusters in tropomyosin do not directly correlate with local bending. Instead, these clusters influence tropomyosin
Area of Science:
- Biochemistry
- Structural Biology
- Molecular Biophysics
Background:
- Actin-tropomyosin binding requires conformational complementarity.
- Alanine clusters in tropomyosin may pre-shape the protein for actin binding.
- Localized bending in tropomyosin could be induced by alanine-induced chain displacement.
Purpose of the Study:
- To investigate the influence of alanine clusters on tropomyosin curvature.
- To determine the relationship between alanine cluster position and tropomyosin structural changes.
- To elucidate the mechanism by which alanine clusters affect tropomyosin conformation.
Main Methods:
- Calculation of longitudinal displacement ('Z-displacement') between tropomyosin coiled-coil chains.
- Analysis of high-resolution crystal structures of tropomyosin fragments.
- Molecular dynamics simulations of full-length alpha-alpha-tropomyosin.
Main Results:
- No direct spatial correlation was found between alanine cluster positions and Z-displacement.
- No direct correspondence was observed between alanine clusters and local tropomyosin curvature.
- Alanine clusters exert a complex, delocalized influence on tropomyosin bending.
Conclusions:
- Alanine clusters do not induce specific local structural changes in tropomyosin.
- The effect of alanine clusters on tropomyosin conformation is complex and widespread.
- Tropomyosin's overall bending pattern is gradually influenced by alanine clusters.
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