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

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 array...

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Published inProceedings of the National Academy of Sciences - PNAS Vol. 108; no. 34; pp. 14097 - 14102
Main Authors Fang, Ping-An, Conway, James F., Margolis, Henry C., Simmer, James P., Beniash, Elia
Format Journal Article
LanguageEnglish
Published United States National Academy of Sciences 23.08.2011
National Acad Sciences
Subjects
Amelogenin - metabolism
Amelogenin - ultrastructure
Animals
Biological Sciences
Biomineralogy
Calcification, Physiologic - physiology
Calcium phosphates
Calcium Phosphates - metabolism
Cryoelectron Microscopy
Crystals
Image Processing, Computer-Assisted
Mice
Minerals
Molecules
Monomers
Nanocomposites
Nanoparticles - chemistry
Oligomers
Peptides
Physiological regulation
Proteins
Self assembly
Tooth enamel
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Summary: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.
Bibliography:Edited by James J. DeYoreo, Lawrence Berkeley National Laboratory, Berkeley, CA, and accepted by the Editorial Board July 7, 2011 (received for review April 19, 2011)
Author contributions: H.C.M. and E.B. designed research; P.-A.F. performed research; J.P.S. contributed new reagents/analytic tools; P.-A.F., J.F.C., and E.B. analyzed data; and E.B. wrote the paper with input from H.C.M.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1106228108