title: High resolution characterization of myosin IIC protein tailpiece and its effect on filament assembly.
abstract: The motor protein nonmuscle myosin II (NMII) must undergo dynamic oligomerization into filaments to perform its cellular functions. A small nonhelical region at the tail of the long coiled-coil region (tailpiece) is a common feature of all dynamically assembling myosin II proteins. This tailpiece is a key regulatory domain affecting NMII filament assembly properties and is subject to phosphorylation in vivo. We previously demonstrated that the positively charged region of the tailpiece binds to assembly-incompetent NMII-C fragments, inducing filament assembly. In the current study, we investigated the molecular mechanisms by which the tailpiece regulates NMII-C self-assembly. Using alanine scan, we found that specific positive and aromatic residues within the positively charged region of the tailpiece are important for inducing NMII-C filament assembly and for filament elongation. Combining peptide arrays with deletion studies allowed us to identify the tailpiece binding sites in the coiled-coil rod. Elucidation of the mechanism by which the tailpiece induces filament assembly permitted us further investigation into the role of tailpiece phosphorylation. Sedimentation and CD spectroscopy identified that phosphorylation of Thr(1957) or Thr(1960) inhibited the ability of the tailpiece to bind the coiled-coil rod and to induce NMII-C filament formation. This study provides molecular insight into the role of specific residues within the NMII-C tailpiece that are responsible for shifting the oligomeric equilibrium of NMII-C toward filament assembly and determining its morphology.
authors: Institute of Chemistry, The Hebrew University of Jerusalem, Safra Campus Givat Ram, Jerusalem 91904.
authors: Masha M
authors: MM
authors: Rosenberg
authors: Department of Biochemistry and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel.
authors: Daniel
authors: D
authors: Ronen
authors: Institute of Chemistry, The Hebrew University of Jerusalem, Safra Campus Givat Ram, Jerusalem 91904.
authors: Noa
authors: N
authors: Lahav
authors: Department of Biochemistry and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel.
authors: Elvira
authors: E
authors: Nazirov
authors: Department of Biochemistry and Molecular Biology, The Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel. Electronic address: shoshr@ekmd.huji.ac.il.
authors: Shoshana
authors: S
authors: Ravid
authors: Institute of Chemistry, The Hebrew University of Jerusalem, Safra Campus Givat Ram, Jerusalem 91904. Electronic address: assaf.friedler@mail.huji.ac.il.
authors: Assaf
authors: A
authors: Friedler
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002942:Circular Dichroism; D006863:Hydrogen-Ion Concentration; D051379:Mice; D008854:Microscopy, Electron / Q000379:methods; D008969:Molecular Sequence Data; D009154:Mutation; D024462:Myosin Type II / Q000737:chemistry / Q000378:metabolism*; D009218:Myosins / Q000737:chemistry; D010455:Peptides / Q000737:chemistry; D010766:Phosphorylation; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D013912:Threonine / Q000737:chemistry
chemical_list: D010455:Peptides; D013912:Threonine; D024462:Myosin Type II; D009218:Myosins