title: Myelin basic protein is a glial microtubule-associated protein -- characterization of binding domains, kinetics of polymerization, and regulation by phosphorylation and a lipidic environment.
abstract: The 18.5-kDa splice isoform of myelin basic protein (MBP) predominates in the adult brain, adhering the cytoplasmic leaflets of the oligodendrocyte membrane together, but also assembling the cytoskeleton at leading edges of membrane processes. Here, we characterized MBP's role as a microtubule-assembly protein (MAP). Using light scattering and sedimentation assays we found that pseudo-phosphorylation of Ser54 (murine 18.5-kDa sequence) significantly enhanced the rate but not the final degree of polymerization. This residue lies within a short KPGSG motif identical to one in tau, a ubiquitous MAP important in neuronal microtubule assembly. Using polypeptide constructs, each comprising one of three major amphipathic α-helical molecular recognition fragments of 18.5-kDa MBP, we identified the N-terminal α1-peptide as sufficient to cause microtubule polymerization, the rate of which was significantly enhanced in the presence of dodecylphosphocholine (DPC) micelles to mimic a lipidic environment.
authors: Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada.
authors: Agata
authors: A
authors: Zienowicz
authors: Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada.
authors: Vladimir V
authors: VV
authors: Bamm
authors: Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada.
authors: Kenrick A
authors: KA
authors: Vassall
authors: Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada. Electronic address: gharauz@uoguelph.ca.
authors: George
authors: G
authors: Harauz
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D019281:Dimerization; D007700:Kinetics; D008051:Lipid Bilayers / Q000737:chemistry*; D008868:Microtubule Proteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D004676:Myelin Basic Protein / Q000737:chemistry*; D009457:Neuroglia / Q000737:chemistry*; D010766:Phosphorylation; D010767:Phosphorylcholine / Q000031:analogs & derivatives* / Q000737:chemistry; D011485:Protein Binding; D014404:Tubulin / Q000737:chemistry*
chemical_list: D008051:Lipid Bilayers; D008868:Microtubule Proteins; D004676:Myelin Basic Protein; D014404:Tubulin; D010767:Phosphorylcholine; C028810:dodecylphosphocholine
keywords: Dodecylphosphocholine (DPC); Intrinsically-disordered proteins; Microtubule-associated proteins; Myelin basic protein; Oligodendrocyte cytoskeleton; Phosphorylation