[Refining the structure of the strongly bound actin-myosin complex by protein docking]

The structure of the strongly bound complex of the globular myosin head and F-actin is a key for understanding some important details of the mechanism of the actin-myosin motor. Current knowledge about the structure is based on the docking of known atomic structures of actin and myosin heads into low-resolution EM electron density maps. To refine the structure, we suggested a new approach based on energy minimization using the ICM-Pro software. The minimization includes rigid-body movement of protein backbone and side chain optimization on the protein interface. Our best model structure is similar to that obtained from EM. It also provides the highest calculated interaction energy and agrees with a number of mutagenesis experiments. Using the structure, we suggest molecular explanations for actin activation of product release from myosin and actin-induced myosin dissociation.