Bridging Soft Interaction and Excluded Volume in Crowded Milieu through Subtle Protein Dynamics

Area of Science:

• Biophysics
• Protein Dynamics
• Macromolecular Crowding

Background:

• Macromolecular crowding impacts biological molecules via excluded volume and soft interactions.
• Distinguishing between these crowding effects has been challenging.
• Understanding crowding is crucial for cellular processes.

Purpose of the Study:

• To investigate the transition between soft and hard regimes in macromolecular crowding.
• To analyze the temperature-dependent dynamics of human serum albumin (HSA) under various crowding conditions.
• To elucidate the asymmetric influence of crowders on protein dynamics and stability.

Main Methods:

• Utilized temperature-dependent dynamics (local and global) of human serum albumin (HSA).
• Employed synthetic crowders: Dextran 40, PEG 8, Ficoll 70, and Dextran 70.
• Analyzed protein domain dynamics and gating motions.

Main Results:

• Identified a transition region bridging soft and hard crowding regimes, independent of crowder type.
• Observed asymmetric responses in HSA domains I and II and gating motion.
• Revealed heterogeneous dynamics and solvent-coupled/decoupled motions in the crowded environment.
• Found a correlation between increased protein stability and eased local domain motion.

Conclusions:

• A distinct transition exists between soft and hard crowding regimes, offering a unified view.
• Crowder influence on HSA is asymmetric, affecting different domains uniquely.
• Protein dynamics in crowded solutions are heterogeneous.
• Protein stability is intrinsically linked to its dynamic behavior in crowded environments.