pH and Charged Mutations Modulate Cold Shock Protein Folding and Stability: A Constant pH Monte Carlo Study

Area of Science:

• Biochemistry
• Computational Biology
• Protein Science

Background:

• Protein folding and stability are crucial in various scientific disciplines.
• Cold shock proteins (Bs-CspB) from Bacillus subtilis are essential for cellular function under cold stress.

Purpose of the Study:

• To investigate the impact of pH changes and charged mutations on the thermal stability of Bs-CspB.
• To identify and evaluate novel mutations that enhance protein stability across different pH environments.

Main Methods:

• Utilized TKSA-MC web server to analyze ionizable residue contributions to thermal stability via protein charge interactions.
• Employed structure-based models in Monte Carlo simulation at constant pH (SBM-CpHMC) to assess mutation effects on folding energy landscapes.

Main Results:

• Identified specific ionizable residues crucial for Bs-CspB thermal stability.
• Proposed and evaluated a new mutation in an optimized Bs-CspB variant, demonstrating its impact on the folding energy landscape.
• Charge rearrangements in the unfolded state were found to be critical for thermal stability.

Conclusions:

• Combined computational methods effectively predict stabilizing mutations for Bs-CspB at various pH levels.
• Gained insights into how mutations affect protein folding at different stages.
• Charge optimization is key for enhancing protein stability in cold shock proteins.