A tensegrity model for hydrogen bond networks in proteins

Area of Science:

• Biophysics
• Structural Biology
• Biochemistry

Background:

• Protein structure is stabilized by various interactions, including covalent bonds, hydrogen bonds, and hydrophobic interactions.
• Previous tensegrity models in biological systems have considered multiple interaction types.
• Hydrogen bonds are proposed to function as independent structural tensile elements in proteins.

Purpose of the Study:

• To investigate the role of hydrogen bonds as the sole stabilizing tensile elements in protein structures.
• To test the hypothesis that the entire hydrogen bond network achieves balance independently of other interactions.
• To explore the implications of hydrogen bond network balance for protein domain and fibrous protein repeat unit stability.

Main Methods:

• Analysis of hydrogen bond networks within proteins, focusing on sidechain-sidechain, sidechain-backbone, and backbone-backbone interactions.
• Comparison of hydrogen bond network balance in globular protein domains and fibrous protein structures.
• Identification of key points in hydrogen bond networks associated with secondary structure demarcations.

Main Results:

• The hydrogen bond network in proteins exhibits tensegrity balance ('closure') across polypeptide chains, globular domains, and fibrous protein repeat units.
• This balance is achieved independently of stronger covalent bonds and weaker hydrophobic interactions.
• Closure is specifically observed in structures with repeating elements, such as globular domains and fibrous protein repeats, but not in simple extended structures.
• Key closure points are identified at sidechain-backbone hydrogen bonds, often coinciding with secondary structure boundaries.

Conclusions:

• The hydrogen bond network in proteins functions as an independent tensegrity system, crucial for structural stability.
• This independent balance explains the defined size of globular protein domains and fibrous protein repeat units.
• Understanding hydrogen bond network closure provides insights into protein folding and stability mechanisms.