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Updated: Jan 15, 2026
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Micro-dissection of Enamel Organ from Mandibular Incisor of Rats Exposed to Environmental Toxicants
Published on: March 29, 2018
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Amelogenin proteolysis orchestrates functional amyloid pathways in enamel development
Emerson Tavares de Sousa1, Larry Ackerman2, Johan Svensson Bonde3
1Department of Preventive and Restorative Dental Sciences, School of Dentistry, University of California, San Francisco, USA.
Summary
Amelogenin protein assembly into nanoribbons, crucial for enamel formation, is clarified. Proteolytic processing by MMP20 regulates this functional amyloid pathway, enabling controlled biomineralization.
Area of Science:
- Biochemistry
- Biomineralization
- Protein self-assembly
Background:
- Amelogenin is the primary protein in developing enamel, forming structures for apatite growth.
- Its self-assembly into nanoribbons resembles functional amyloids, but mechanisms are unclear.
Purpose of the Study:
- To elucidate the molecular mechanisms of amelogenin (rH174) and its MMP20 cleavage products' assembly pathways.
- To investigate how proteolytic processing influences amelogenin's supramolecular organization and enamel matrix formation.
Main Methods:
- Atomic force microscopy (AFM)
- Transmission electron microscopy (TEM)
- Spectroscopic analyses
- Studied full-length rH174 and C-terminally truncated rH146, including cross-seeding experiments.
Main Results:
- Both rH174 and rH146 assemble via nucleated conformational conversion into β-sheet-rich nanoribbons.
- rH146 shows rapid nucleation and maturation, while rH174 has a delayed pathway.
- Cross-seeding accelerates rH174 assembly, mimicking in vivo conditions.
- The MMP20 cleavage product TRAP does not form nanoribbons, altering the pathway.
Conclusions:
- Proteolysis-triggered assembly pathways regulate amelogenin's supramolecular structure for enamel biomineralization.
- Amelogenin functions as a tunable vertebrate functional amyloid.
- MMP20 processing controls matrix formation, preventing premature crystal fusion during amelogenesis.
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