Nearly symmetrical proteins: folding pathways and transition states

Area of Science:

• Protein folding dynamics
• Computational biophysics
• Statistical mechanics

Background:

• The B domain of protein A folding has been extensively studied using experimental and computational methods.
• Previous models suggested multiple folding pathways influenced by temperature and denaturant concentration, but experimental data did not fully support this.
• Discrepancies exist between theoretical predictions and experimental observations of protein A's folding behavior.

Purpose of the Study:

• To investigate protein folding pathways using a refined statistical mechanical model.
• To reconcile computational predictions with experimental findings on protein A's B domain folding.
• To explore the role of contact energies in determining protein folding pathways.

Main Methods:

• Kinetic simulations based on a statistical mechanical model.
• Analysis of four nearly symmetrical proteins, including protein A's B domain.
• Direct sampling of the transition state in protein folding.

Main Results:

• The refined model, incorporating accurate contact energies, predicts a dominant folding pathway for protein A's B domain.
• This simulated pathway aligns with recent experimental observations.
• The study successfully sampled the transition state, providing insights into the folding mechanism.

Conclusions:

• Accurate contact energies are crucial for predicting protein folding pathways.
• A single dominant pathway, rather than multiple pathways, characterizes the folding of protein A's B domain under physiological conditions.
• The simplified model offers a valuable tool for understanding protein folding dynamics and transition states.