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Direct evidence that KLK4 is a hydroxyapatite-binding protein.
Vidal A Perez1, Jonathan E Mangum2, Michael J Hubbard3
1Department of Pharmacology & Therapeutics, The University of Melbourne, Victoria, Australia; Department of Pediatric Stomatology, University of Talca, Talca, Chile.
Biochemical and Biophysical Research Communications
|December 13, 2017
Summary
Kallikrein 4 (KLK4) protease binds hydroxyapatite and self-destructs after degrading amelogenin, impacting dental enamel formation. This clarifies KLK4
Area of Science:
- Biochemistry
- Developmental Biology
- Mineralized Tissue Biology
Background:
- Kallikrein 4 (KLK4) is crucial for dental enamel maturation, degrading amelogenin.
- KLK4 dysfunction causes enamel developmental defects, but its retention mechanism is unknown.
- Conflicting data exists regarding KLK4's affinity for hydroxyapatite.
Purpose of the Study:
- To investigate the direct binding of KLK4 to hydroxyapatite.
- To elucidate the auto-degradation mechanism of KLK4.
- To understand KLK4's role in enamel hardening and malformation.
Main Methods:
- Biochemical analyses using pure components under quasi-physiological conditions.
- Incubation of KLK4 with and without substrate (including a proxy substrate).
- Assessment of KLK4 activity, aggregation, and fragmentation.
Main Results:
- KLK4 directly binds to hydroxyapatite.
- KLK4 loses activity, aggregates, and autofragments when incubated without substrate.
- KLK4 remains active and intact when a non-ionic detergent serves as a proxy substrate.
Conclusions:
- KLK4's direct binding to hydroxyapatite influences its retention in the enamel matrix.
- KLK4 undergoes auto-degradation after amelogenin breakdown, suggesting a substrate-dependent stability.
- These findings propose a new model for KLK4 function in enamel hardening and defects.
