title: Skip residues modulate the structural properties of the myosin rod and guide thick filament assembly.
abstract: The rod of sarcomeric myosins directs thick filament assembly and is characterized by the insertion of four skip residues that introduce discontinuities in the coiled-coil heptad repeats. We report here that the regions surrounding the first three skip residues share high structural similarity despite their low sequence homology. Near each of these skip residues, the coiled-coil transitions to a nonclose-packed structure inducing local relaxation of the superhelical pitch. Moreover, molecular dynamics suggest that these distorted regions can assume different conformationally stable states. In contrast, the last skip residue region constitutes a true molecular hinge, providing C-terminal rod flexibility. Assembly of myosin with mutated skip residues in cardiomyocytes shows that the functional importance of each skip residue is associated with rod position and reveals the unique role of the molecular hinge in promoting myosin antiparallel packing. By defining the biophysical properties of the rod, the structures and molecular dynamic calculations presented here provide insight into thick filament formation, and highlight the structural differences occurring between the coiled-coils of myosin and the stereotypical tropomyosin. In addition to extending our knowledge into the conformational and biological properties of coiled-coil discontinuities, the molecular characterization of the four myosin skip residues also provides a guide to modeling the effects of rod mutations causing cardiac and skeletal myopathies.
authors.affiliation: Department of Biochemistry, University of Wisconsin, Madison, WI 53706;
authors.forename: Keenan C
authors.initials: KC
authors.lastname: Taylor
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology and Bio Frontiers Institute, University of Colorado, Boulder, CO 80309;
authors.forename: Massimo
authors.initials: M
authors.lastname: Buvoli
authors.affiliation: Department of Chemistry and Theoretical Chemistry Institute, University of Wisconsin, Madison, WI 53706.
authors.forename: Elif Nihal
authors.initials: EN
authors.lastname: Korkmaz
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology and Bio Frontiers Institute, University of Colorado, Boulder, CO 80309;
authors.forename: Ada
authors.initials: A
authors.lastname: Buvoli
authors.affiliation: Department of Chemistry and Theoretical Chemistry Institute, University of Wisconsin, Madison, WI 53706.
authors.forename: Yuqing
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: Department of Biochemistry, University of Wisconsin, Madison, WI 53706;
authors.forename: Nathan T
authors.initials: NT
authors.lastname: Heinze
authors.affiliation: Department of Chemistry and Theoretical Chemistry Institute, University of Wisconsin, Madison, WI 53706 cui@chem.wisc.edu Leslie.Leinwand@colorado.edu ivan_rayment@biochem.wisc.edu.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Cui
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology and Bio Frontiers Institute, University of Colorado, Boulder, CO 80309; cui@chem.wisc.edu Leslie.Leinwand@colorado.edu ivan_rayment@biochem.wisc.edu.
authors.forename: Leslie A
authors.initials: LA
authors.lastname: Leinwand
authors.affiliation: Department of Biochemistry, University of Wisconsin, Madison, WI 53706; cui@chem.wisc.edu Leslie.Leinwand@colorado.edu ivan_rayment@biochem.wisc.edu.
authors.forename: Ivan
authors.initials: I
authors.lastname: Rayment
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry*; D024722:Cardiac Myosins / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000737:chemistry* / Q000378:metabolism*; D015879:Myosin Subfragments / Q000737:chemistry* / Q000378:metabolism*; D018583:Pliability; D055550:Protein Stability; D017433:Protein Structure, Secondary; D020449:Repetitive Sequences, Amino Acid; D012518:Sarcomeres / Q000378:metabolism; D017384:Sequence Deletion; D013329:Structure-Activity Relationship
chemical_list: D000596:Amino Acids; C501641:MYH7 protein, human; D050505:Mutant Proteins; D015879:Myosin Subfragments; D024722:Cardiac Myosins; D018995:Myosin Heavy Chains
keywords: cardiac/skeletal myopathies; coiled-coils; molecular dynamics; myosin; protein structure