Mechanical response and conformational changes of alpha-actinin domains during unfolding: a molecular dynamics study |
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Authors: | Monica Soncini Simone Vesentini Davide Ruffoni Mario Orsi Marco A Deriu Alberto Redaelli |
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Institution: | (1) Department of Bioengineering, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan, Italy;(2) Department of Biomaterials, Max-Planck-Institute of Colloids and Interfaces, Potsdam, Germany;(3) School of Chemistry, Southampton University, Southampton, United Kingdom;(4) Department of Mechanics, Politecnico di Torino, Turin, Italy |
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Abstract: | Alpha-actinin is a cytoskeleton-binding protein involved in the assembly and regulation of the actin filaments. In this work
molecular dynamics method was applied to investigate the mechanical behaviour of the human skeletal muscle α-actinin. Five
configurations were unfolded at an elongation speed of 0.1 nm/ps in order to investigate the conformational changes occurring
during the extension process. Moreover, a sensitivity analysis at different velocities was performed for one of the R2–R3
spectrin-like repeat configuration extracted in order to evaluate the effect of the pulling speed on the mechanical behaviour
of the molecule. Two different behaviours were recognized with respect to the pulling speed. In particular, at speed higher
than 0.025 nm/ps a continuous rearrangement without evident force peaks was obtained, on the contrary at lower speed evident
peaks in the range 500–750 pN were detected. R3 repeat resulted more stable than R2 during mechanical unfolding, due to the
lower hydrophobic surface available to the solvent. The characterization of the R2–R3 units can be useful for the development
of cytoskeleton network models based on stiffness values obtained by analyses performed at the molecular level. |
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Keywords: | Alpha-actinin Molecular dynamics Mechanical unfolding |
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