Nonlinear backbone torsional pair correlations in proteins.

Area of Science:

• Biophysics
• Structural Biology
• Computational Biology

Background:

• Protein allostery relies on dynamic structural correlations, but their physical origins remain unclear.
• Decades of research have yet to fully elucidate the mechanisms behind allosteric regulation in proteins.

Purpose of the Study:

• To investigate the nature and origin of dynamical structural correlations in proteins.
• To identify the specific types of residue interactions and motions that contribute to allosteric effects.
• To propose a strategy for finding novel allosteric modulation sites.

Main Methods:

• Analysis of molecular dynamics (MD) simulation trajectories for ten diverse proteins.
• Examination of backbone torsional pair (BTP) correlations, focusing on nonlinear and linear types.
• Investigation of the association between torsional motion, state transitions, and local dynamics.

Main Results:

• Nonlinear BTP correlations, primarily long-ranged and involving loop residues, are prevalent in most proteins studied.
• These nonlinear correlations are linked to anharmonic torsional state transitions and anisotropic local motions on longer timescales.
• In contrast, correlations in stable secondary structures (α-helices, β-strands) are linear, short-ranged, and associated with harmonic local motions.
• Heterogeneous linear correlations were identified as the direct cause of nonlinear contributions.

Conclusions:

• Nonlinear backbone torsional pair correlations are a significant factor in protein allostery.
• The findings suggest a generalizable approach for identifying novel allosteric modulation sites.
• Understanding these dynamics provides insights into protein function and regulation.