Protein Fluctuations and Cavity Changes Relationship.

Area of Science:

• Structural Biology
• Computational Biology
• Biophysics

Background:

• Protein cavities and tunnels are essential for biological functions like ligand binding and catalysis.
• Cavity rearrangements are necessary for these functions, highlighting the importance of protein flexibility.
• Protein vibrational dynamics govern cavity flexibility, but characterizing this dynamics is challenging.

Purpose of the Study:

• To develop a novel method for characterizing protein cavity dynamics.
• To quantify cavity flexibility using molecular dynamics simulations and volume gradient vectors.
• To investigate the relationship between vibrational modes and cavity volume changes.

Main Methods:

• Utilized molecular dynamics (MD) simulations to capture protein conformational plasticity.
• Developed algorithms for robust cavity volume calculation and numerical differentiation.
• Applied principal component analysis (PCA) to MD trajectories to define the volume gradient vector.
• Analyzed the frequency and delocalization of principal component modes contributing to the volume gradient.

Main Results:

• Identified a novel procedure to characterize protein cavity dynamics via volume gradient vectors.
• Found that low-frequency vibrational modes are critical for cavity volume changes.
• Observed that concerted motions of residues lining the cavity are associated with these low-frequency modes.
• Demonstrated that proteins with significant low-frequency contributions to volume fluctuations exhibit enhanced cavity flexibility.

Conclusions:

• Low-frequency collective motions are key determinants of protein cavity flexibility.
• The developed volume gradient vector approach provides a robust measure of cavity dynamics.
• This method offers insights into how protein dynamics facilitate essential biological functions.