title: Intrinsically disordered enamel matrix protein ameloblastin forms ribbon-like supramolecular structures via an N-terminal segment encoded by exon 5.
abstract: Tooth enamel, the hardest tissue in the body, is formed by the evolutionarily highly conserved biomineralization process that is controlled by extracellular matrix proteins. The intrinsically disordered matrix protein ameloblastin (AMBN) is the most abundant nonamelogenin protein of the developing enamel and a key element for correct enamel formation. AMBN was suggested to be a cell adhesion molecule that regulates proliferation and differentiation of ameloblasts. Nevertheless, detailed structural and functional studies on AMBN have been substantially limited by the paucity of the purified nondegraded protein. With this study, we have developed a procedure for production of a highly purified form of recombinant human AMBN in quantities that allowed its structural characterization. Using size exclusion chromatography, analytical ultracentrifugation, transmission electron, and atomic force microscopy techniques, we show that AMBN self-associates into ribbon-like supramolecular structures with average widths and thicknesses of 18 and 0.34 nm, respectively. The AMBN ribbons exhibited lengths ranging from tens to hundreds of nm. Deletion analysis and NMR spectroscopy revealed that an N-terminal segment encoded by exon 5 comprises two short independently structured regions and plays a key role in self-assembly of AMBN.
authors.affiliation: Institute of Microbiology, Academy of Sciences of the Czech Republic, 142 20 Prague, Czech Republic.
authors.forename: Tomas
authors.initials: T
authors.lastname: Wald
authors.forename: Adriana
authors.initials: A
authors.lastname: Osickova
authors.forename: Miroslav
authors.initials: M
authors.lastname: Sulc
authors.forename: Oldrich
authors.initials: O
authors.lastname: Benada
authors.forename: Alena
authors.initials: A
authors.lastname: Semeradtova
authors.forename: Lenka
authors.initials: L
authors.lastname: Rezabkova
authors.forename: Vaclav
authors.initials: V
authors.lastname: Veverka
authors.forename: Lucie
authors.initials: L
authors.lastname: Bednarova
authors.forename: Jan
authors.initials: J
authors.lastname: Maly
authors.forename: Pavel
authors.initials: P
authors.lastname: Macek
authors.forename: Peter
authors.initials: P
authors.lastname: Sebo
authors.forename: Ivan
authors.initials: I
authors.lastname: Slaby
authors.forename: Jiri
authors.initials: J
authors.lastname: Vondrasek
authors.forename: Radim
authors.initials: R
authors.lastname: Osicka
mesh_terms: D002850:Chromatography, Gel; D002942:Circular Dichroism; D003746:Dental Enamel Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005091:Exons; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: C490889:AMBN protein, human; D003746:Dental Enamel Proteins; D011994:Recombinant Proteins
keywords: Ameloblastin; Amelogenin; Extracellular Matrix Proteins; Intrinsically Disordered Proteins; Protein Purification; Protein Self-assembly; Tooth