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J Biol Chem. 2015 Jan 16;290(3):1679-88. doi: 10.1074/jbc.M114.606665. Epub 2014 Nov 21.

Structural model of weak binding actomyosin in the prepowerstroke state.

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From the Department of Biochemistry, Institute of Biology and.
From the Department of Biochemistry, Institute of Biology and the ELTE-HAS Molecular Biophysics Research Group, Eötvös Loránd University, H-1117 Budapest and Optopharma Ltd., H-1015 Budapest, Hungary


We present the first in silico model of the weak binding actomyosin in the initial powerstroke state, representing the actin binding-induced major structural changes in myosin. First, we docked an actin trimer to prepowerstroke myosin then relaxed the complex by a 100-ns long unrestrained molecular dynamics. In the first few nanoseconds, actin binding induced an extra primed myosin state, i.e. the further priming of the myosin lever by 18° coupled to a further closure of switch 2 loop. We demonstrated that actin induces the extra primed state of myosin specifically through the actin N terminus-activation loop interaction. The applied in silico methodology was validated by forming rigor structures that perfectly fitted into an experimentally determined EM map of the rigor actomyosin. Our results unveiled the role of actin in the powerstroke by presenting that actin moves the myosin lever to the extra primed state that leads to the effective lever swing.


Actin; Enzyme Cycle; Enzyme Kinetics; Enzyme Mechanism; Molecular Dynamics; Myosin; Powerstroke; Protein Structure; Structural Model

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