Microsolvation Effect on the Twist of β-sheets

Area of Science:

• Computational chemistry
• Biophysics
• Protein structure

Background:

• Beta-sheets (β-sheets) are fundamental protein secondary structures.
• These structures can adopt either flat or twisted conformations.
• The preference for twisted β-sheets under specific conditions is not fully understood.

Purpose of the Study:

• To investigate the influence of microsolvation on β-sheet conformation.
• To elucidate the driving forces behind the preference for twisted β-sheets.
• To explore the role of strain and hydrogen bonding in β-sheet twisting.

Main Methods:

• Density functional theory (DFT) calculations were employed.
• Investigation of bare and microsolvated parallel and antiparallel two-strand polyalanine β-sheets.
• Full geometry optimizations were performed.

Main Results:

• Microsolvation was found to increase interstrand twisting in β-sheets.
• A transition from flat to twisted conformations was promoted by microsolvation.
• This transition is linked to compressive strain induced by water molecules.
• Residues adapt local twists to release strain and enhance water-water hydrogen bonding.

Conclusions:

• Microsolvation plays a significant role in inducing β-sheet twisting.
• Compressive strain and favorable water-water interactions are key factors.
• The findings are supported by analyses of protein crystal structures.