Residue-Specific Insights into the Intermolecular Protein-Protein Interfaces Driving Amelogenin Self-Assembly in...

Area of Science:

• Biochemistry
• Structural Biology
• Biophysics

Background:

• Amelogenin is the main protein in developing tooth enamel.
• Its self-assembly into oligomers and nanospheres is vital for enamel mineralization.
• Previous studies faced challenges in analyzing these structures in solution.

Purpose of the Study:

• To investigate the self-association of amelogenin at different pH levels.
• To identify the protein regions involved in amelogenin quaternary structure formation.
• To characterize the structural dynamics of amelogenin oligomers and nanospheres.

Main Methods:

• Utilized perdeuterated murine amelogenin.
• Employed TROSY-based NMR spectroscopy to analyze protein structure and dynamics.
• Studied amelogenin over a pH range of 5.5 to 8.0.

Main Results:

• Assigned 1H-15N spectra of amelogenin, revealing changes in dynamics and protein-protein interfaces.
• Identified specific N-terminal and central hydrophobic regions involved in oligomer and nanosphere formation.
• Observed a disordered and mobile C-terminus, suggesting it is solvent-exposed in nanospheres.

Conclusions:

• Amelogenin self-assembly is driven by specific intermolecular interfaces, primarily at the N-terminus and central regions.
• Nanosphere structures feature disordered, solvent-exposed C-termini.
• These findings provide residue-specific insights into amelogenin's role in enamel biomineralization.