Mechanistic insights into the active site and allosteric communication pathways in human nonmuscle myosin-2C
Krishna Chinthalapudi,
Sarah M Heissler,
Matthias Preller,
James R Sellers,
Dietmar J Manstein
Affiliations
Krishna Chinthalapudi
Institute for Biophysical Chemistry, OE4350, Hannover Medical School, Hannover, Germany; Division for Structural Biochemistry, OE8830, Hannover Medical School, Hannover, Germany; Cell Adhesion Laboratory, Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter, United States
Sarah M Heissler
Institute for Biophysical Chemistry, OE4350, Hannover Medical School, Hannover, Germany; Laboratory of Molecular Physiology, NHLBI, National Institutes of Health, Bethesda, United States
Institute for Biophysical Chemistry, OE4350, Hannover Medical School, Hannover, Germany; Centre for Structural Systems Biology (CSSB), German Electron Synchrotron (DESY), Hamburg, Germany
Institute for Biophysical Chemistry, OE4350, Hannover Medical School, Hannover, Germany; Division for Structural Biochemistry, OE8830, Hannover Medical School, Hannover, Germany
Despite a generic, highly conserved motor domain, ATP turnover kinetics and their activation by F-actin vary greatly between myosin-2 isoforms. Here, we present a 2.25 Å pre-powerstroke state (ADP⋅VO4) crystal structure of the human nonmuscle myosin-2C motor domain, one of the slowest myosins characterized. In combination with integrated mutagenesis, ensemble-solution kinetics, and molecular dynamics simulation approaches, the structure reveals an allosteric communication pathway that connects the distal end of the motor domain with the active site. Disruption of this pathway by mutation of hub residue R788, which forms the center of a cluster of interactions connecting the converter, the SH1-SH2 helix, the relay helix, and the lever, abolishes nonmuscle myosin-2 specific kinetic signatures. Our results provide insights into structural changes in the myosin motor domain that are triggered upon F-actin binding and contribute critically to the mechanochemical behavior of stress fibers, actin arcs, and cortical actin-based structures.
