Glassy Dynamics and Memory Effects in an Intrinsically Disordered Protein Construct

Area of Science:

• Biophysics
• Protein Dynamics
• Soft Matter Physics

Background:

• Globular proteins exhibit glassy, nonexponential relaxations attributed to conformational dynamics.
• Intrinsically disordered proteins (IDPs) were thought to lack these characteristics.
• Understanding IDP dynamics is crucial for their biological functions.

Purpose of the Study:

• To investigate the presence of glassy dynamics in intrinsically disordered proteins.
• To identify the underlying mechanisms responsible for these dynamics in IDPs.
• To explore the implications of these findings for the broader class of disordered proteins.

Main Methods:

• Single-molecule experiments applying controlled tension to a disordered protein construct.
• Analysis of relaxation dynamics, specifically logarithmic relaxations and Kovacs memory effect.
• Development and validation of a theoretical model predicting force-dependent relaxation.

Main Results:

• Demonstrated two key signatures of glassy dynamics (logarithmic relaxations, Kovacs memory effect) in a single disordered protein molecule.
• Identified the presence of multiple independent local structures within the disordered protein chain.
• Developed a model that accurately predicts the force dependence of these relaxation dynamics.

Conclusions:

• Intrinsically disordered proteins can exhibit glassy dynamics, challenging previous assumptions.
• Multiple local structures within the protein chain are responsible for these observed dynamics.
• The proposed mechanism is likely generalizable to other disordered proteins.