Molecular packing of myosin II coiled-coil rods into myosin filaments and the role of skip residues in the heptad sequence have been investigated. Sequence comparison of rods from skeletal, smooth and non-muscle myosin II shows that different myosin II subtypes have significantly different charge distributions. Analysis of the ionic interactions between adjacent rods with changing molecular overlap relates the different patterns of charge to the different structures of skeletal and smooth muscle myosin II filaments. It is shown in the case of skeletal muscle myosin II that the skip residues have a critical role in keeping these unique patterns of charge in perfect phase. Only one of the previously suggested packing models for myosin II filaments, with a slight modification, is supported, since it satisfies all the sequence-predicted axial shifts between adjacent rods. Such analysis significantly advances understanding of myosin filament assembly properties and will help to provide a basis for the proper understanding of myosin-associated diseases.
Bibliographical noteFunding Information:
We thank Shaikeh Hollander for help with Excel macro programming; Michal Rivlin-Etzion and Rafi Bistritzer for help with Fourier transforms; Ravid's laboratory members for helpful discussions. J.M.S. acknowledges support of the British Heart Foundation (no. PG/02/054/13776) for current work on myosin filament structure.
- Bipolar myosin filaments
- Coiled-coil skip residues
- Myosin II rod sequences
- Myosin filament structure
- Side-polar myosin filaments