Structural domains and main-chain flexibility in prion proteins.

Area of Science:

• Biophysics
• Structural Biology
• Computational Biology

Background:

• Prion proteins are crucial in neurodegenerative diseases.
• Understanding prion protein structure and dynamics is key to elucidating misfolding mechanisms.
• Conventional methods have limitations in characterizing protein flexibility and domain dynamics.

Purpose of the Study:

• To develop and validate a novel computational approach for defining structural domains and characterizing local flexibility in prion proteins.
• To identify regions of low stability within prion proteins that may facilitate misfolding.
• To provide a framework for quantitative assessment of spontaneous prion protein misfolding routes.

Main Methods:

• Utilizing a comprehensive theory of collective protein dynamics.
• Applying principal component analysis to molecular dynamics trajectories to determine essential collective coordinates.
• Simulating high-temperature unfolding of human prion protein.

Main Results:

• Successfully identified dynamic domains and characterized local main-chain flexibility for human and chicken prion proteins.
• Validated the approach by comparing predicted domains and flexibility profiles with experimental data (NMR-derived random coil indexes), showing excellent agreement.
• Demonstrated that dynamic domains offer a sensitive measure of protein collective structure and dynamics, revealing properties beyond conventional secondary structure analysis.
• Identified potential low-stability regions associated with beta-sheet (strands S1 and S2) and adjacent loops in human prion protein unfolding.

Conclusions:

• The novel collective dynamics approach accurately defines structural domains and local flexibility in prion proteins.
• This method provides a sensitive tool for analyzing protein collective structure and dynamics, surpassing conventional techniques.
• The findings suggest specific regions in prion proteins, particularly the S1-S2 beta-sheet and associated loops, are susceptible to unfolding, offering insights into misfolding pathways.