Dynamic Structural Changes and Thermodynamics in Phase Separation Processes of an Intrinsically Disordered-Ordered...

Area of Science:

• Biochemistry
• Biophysics
• Materials Science

Background:

• Elastin-like proteins (ELPs) are crucial biological molecules and models for intrinsically disordered proteins (IDPs).
• ELPs exhibit dynamic structural transitions linked to coacervates and liquid-liquid phase transitions.
• The precise conformational state of ELPs below and above coacervation temperature and its role in phase separation remain unclear.

Purpose of the Study:

• To investigate the conformational changes of ELPs during coacervation.
• To determine the role of specific conformations in the phase separation of ELPs.
• To explore the implications for designing protein-based smart materials.

Main Methods:

• Utilized matrix least-squares global Boltzmann fitting of circular dichroism spectra.
• Analyzed ELPs with varying repeat units: (VPGVG)20, (VPGVG)40, and (VPGVG)60.
• Characterized coacervate suspensions using differential scattering.

Main Results:

• Coacervation was observed to occur sharply at a conformational threshold, approximately 20 repeat units adopting a β-turn structure.
• The identified β-turn fraction was retained within the assembled polypeptides in the coacervate state.
• A correlation between conformational status and phase separation was established.

Conclusions:

• A specific number of repeat units acquiring β-turn conformation acts as a trigger for ELP coacervation.
• This conformational threshold plays a role in the assembly of ELPs and potentially other protein systems.
• Findings provide insights for the rational design of advanced protein-based smart materials.