The effect of recombinant mouse amelogenins on the formation and organization of hydroxyapatite crystals in vitro

Amelogenin is the most abundant protein in developing dental enamel. It is believed to play an important role in the regulation of the growth and organization of enamel crystals. Amelogenin, unlike many other proteins found in biominerals, is mostly hydrophobic except for a 13 amino acid hydrophilic...

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Bibliographic Details
Published in:Journal of structural biology 2005-02, Vol.149 (2), p.182-190
Main Authors: Beniash, Elia, Simmer, James P., Margolis, Henry C.
Format: Article
Language:English
Subjects:
Amelogenin
Amino Acid Sequence
Animals
Biomineralization
Calcium phosphate
Calcium Phosphates - chemistry
Crystal growth
Crystallization
Dental Enamel - chemistry
Dental Enamel Proteins - chemistry
Dental Enamel Proteins - genetics
Dental Enamel Proteins - metabolism
Dental Enamel Proteins - ultrastructure
Durapatite - chemistry
Enamel
Hydrophobic and Hydrophilic Interactions
In Vitro Techniques
Mice
Molecular Sequence Data
Nanotubes - ultrastructure
Protein Structure, Tertiary
Recombinant Proteins - chemistry
Recombinant Proteins - metabolism
Recombinant Proteins - ultrastructure
Self-assembly
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Summary:Amelogenin is the most abundant protein in developing dental enamel. It is believed to play an important role in the regulation of the growth and organization of enamel crystals. Amelogenin, unlike many other proteins found in biominerals, is mostly hydrophobic except for a 13 amino acid hydrophilic C-terminal domain. To clarify the role of amelogenin in enamel mineralization, we designed calcium phosphate crystal growth experiments in the presence of recombinant amelogenins with or without the charged C-terminal domain. The shape and organization of the crystals were examined by TEM in bright field and diffraction modes. It was found that both full-length and truncated amelogenin inhibit crystal growth in directions normal to the c-axis. At the same time, crystallites organized into parallel arrays only in the presence of the full-length amelogenin in monomeric form. Pre-assembled amelogenins had no effect on crystals organization. These results imply that the hydrophobic portion of amelogenin plays a role in an inhibition of crystal growth, whereas the C-terminal domain is essential for the alignment of crystals into parallel arrays. Our data also suggest that nascent enamel structure emerges as a result of cooperative interactions between forming crystals and assembling proteins.
ISSN:1047-8477
1095-8657
DOI:10.1016/j.jsb.2004.11.001