Role of Macromolecular Assembly of Enamel Matrix Proteins in Enamel Formation

Margolis, Henry C.; Beniash, Elia; Fowler, Christabel E.

doi:10.1177/154405910608500902

Cited by 261 publications

(367 citation statements)

References 177 publications

(247 reference statements)

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“…However, there does appear to be a propensity towards positive Δδ 13 C α values and negative Δδ 13 C β values, suggesting a predisposition towards β-strand character. This observation corroborates with CD and SAXS studies that suggest monomeric amelogenin adopts an extended β-strand/β-spiral/ polyprolineII type structure in solution (Margolis et al 2006). Efforts are in progress to address the extent of such an extended structure via the analysis of 3 J HNα coupling constants and NOE data (Parrot et al 2002).…”

Section: Resultssupporting

confidence: 82%

1H, 13C, and 15N resonance assignments of murine amelogenin, an enamel biomineralization protein

et al. 2008

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Section: Resultssupporting

confidence: 82%

1H, 13C, and 15N resonance assignments of murine amelogenin, an enamel biomineralization protein

et al. 2008

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“…Dental enamel is a prime example of a biomineralization system, which serves as a model for understanding basic mechanisms that regulate biomineral formation (1)(2)(3). Enamel is the most mineralized tissue in the body, possessing exceptional mechanical properties that combine high hardness with remarkable resilience (4), which are determined largely by its unique structural organization.…”

mentioning

confidence: 99%

“…Amelogenin transiently stabilizes amorphous calcium phosphate (ACP) and regulates the formation of parallel arrays of mineral crystallites (8,9). It is comprised of three domains: an N-terminal tyrosine-rich amelogenin peptide (TRAP), a charged C-terminal hydrophilic telopeptide (C telopeptide), and a central domain rich in X-Y-Pro repeats (2). Amelogenin in solution is globally unfolded with some regions containing extended β-sheets and polyproline type II helices (10,11).…”

mentioning

confidence: 99%

Hierarchical self-assembly of amelogenin and the regulation of biomineralization at the nanoscale

Fang

Conway

Margolis³

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

179

184

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Enamel is a highly organized hierarchical nanocomposite, which consists of parallel arrays of elongated apatitic crystallites forming an intricate three-dimensional microstructure. Amelogenin, the major extracellular matrix protein of dental enamel, regulates the formation of these crystalline arrays via cooperative interactions with forming mineral phase. Using cryoelectron microscopy, we demonstrate that amelogenin undergoes stepwise hierarchical self-assembly. Furthermore, our results indicate that interactions between amelogenin hydrophilic C-terminal telopeptides are essential for oligomer formation and for subsequent steps of hierarchical self-assembly. We further show that amelogenin assemblies stabilize mineral prenucleation clusters and guide their arrangement into linear chains that organize as parallel arrays. The prenucleation clusters subsequently fuse together to form needle-shaped mineral particles, leading to the formation of bundles of crystallites, the hallmark structural organization of the forming enamel at the nanoscale. These findings provide unique insight into the regulation of biological mineralization by specialized macromolecules and an inspiration for bottom-up strategies for the materials design.

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“…A number of proteins were identified in the transient enamel matrix, with amelogenin constituting more than 90% of the enamel matrix. Amelogenin is a fairly hydrophobic protein comprised of N-terminal tyrosine-rich domain (TRAP), central proline-rich domain, and a C-terminal hydrophilic telopeptide (19). Amelogenin monomers adopt an extended conformation in solution with a large fraction of PPII type helix (20 -24).…”

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confidence: 99%

Amelogenin-Collagen Interactions Regulate Calcium Phosphate Mineralization in Vitro

Deshpande

Fang

Simmer

et al. 2010

Journal of Biological Chemistry

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Collagen and amelogenin are two major extracellular organic matrix proteins of dentin and enamel, the mineralized tissues comprising a tooth crown. They both are present at the dentinenamel boundary (DEB), a remarkably robust interface holding dentin and enamel together. It is believed that interactions of dentin and enamel protein assemblies regulate growth and structural organization of mineral crystals at the DEB, leading to a continuum at the molecular level between dentin and enamel organic and mineral phases. To gain insight into the mechanisms of the DEB formation and structural basis of its mechanical resiliency we have studied the interactions between collagen fibrils, amelogenin assemblies, and forming mineral in vitro, using electron microscopy. Our data indicate that collagen fibrils guide assembly of amelogenin into elongated chain or filament-like structures oriented along the long axes of the fibrils. We also show that the interactions between collagen fibrils and amelogenin-calcium phosphate mineral complexes lead to oriented deposition of elongated amorphous mineral particles along the fibril axes, triggering mineralization of the bulk of collagen fibril. The resulting structure was similar to the mineralized collagen fibrils found at the DEB, with arrays of smaller well organized crystals inside the collagen fibrils and bundles of larger crystals on the outside of the fibrils. These data suggest that interactions between collagen and amelogenin might play an important role in the formation of the DEB providing structural continuity between dentin and enamel.Dentin and enamel, the two mineralized tissues that comprise a tooth crown, are strikingly different in terms of their compositional, structural, and mechanical properties (1). Despite these differences, dentin and enamel work together for decades under severe mechanical stress, without delamination or catastrophic failure.Dentin is a mineralized tissue similar to bone, comprised primarily of fibrillar collagen type I, carbonated apatite and water (2). There are other so-called noncollagenous macromolecules present that, in total, represent less then 10% by mass of organic material, although they play important roles in the formation and function of these tissues. All bone materials share the same basic building block, a collagen fibril, in which plateshaped apatitic crystals are organized in parallel arrays with their c-axes co-aligned with the long axis of the fibril (2-4). Collagen type I triple helical molecules, are super-coiled assemblies of two identical ␣1-chains and one ␣2-chain with a different sequence (5, 6). Each chain contains more than 1000 amino acids and is primarily composed of Gly-X-Y repeats, where amino acids proline (Pro) and hydroxyproline (Hyp) predominantly occupy X and Y positions. All three chains in the molecule adopt a polyproline II (PPII)-like structure, which is stabilized by direct and water mediated inter-and intra-chain hydrogen bonds (5, 6). Collagen fibrils form via a self-assembly process in which collag...

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Role of Macromolecular Assembly of Enamel Matrix Proteins in Enamel Formation

Cited by 261 publications

References 177 publications

1H, 13C, and 15N resonance assignments of murine amelogenin, an enamel biomineralization protein

1H, 13C, and 15N resonance assignments of murine amelogenin, an enamel biomineralization protein

Hierarchical self-assembly of amelogenin and the regulation of biomineralization at the nanoscale

Amelogenin-Collagen Interactions Regulate Calcium Phosphate Mineralization in Vitro

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