Microphase Separation Produces Interfacial Environment within Diblock Biomolecular Condensates.

Area of Science:

• Biochemistry
• Cell Biology
• Biophysics

Background:

• Phase separation of intrinsically disordered proteins is key to cellular organization.
• Connecting protein sequences to condensate properties (molecular grammar) is challenging due to limited high-resolution structural data.

Purpose of the Study:

• To investigate the relationship between amino acid sequences and the physical properties of protein condensates.
• To explore the internal structure and stability mechanisms of elastin-like polypeptide (ELP) condensates.

Main Methods:

• Multiscale simulations were employed to model ELP systems.
• Fluorescence lifetime imaging microscopy (FLIM) experiments were conducted.
• Environmentally sensitive fluorophores were used to probe microenvironments.

Main Results:

• Simulations accurately predicted how amino acid substitutions affect condensate stability.
• Distinct microenvironments within single condensates were identified and experimentally verified.
• Condensate stability correlates with interfacial hydrophobicity and protein-water hydrogen bonds due to residue interspersion and lack of secondary structure.

Conclusions:

• The study uncovers novel mechanisms governing condensate stability and organization.
• The findings provide insights into the molecular grammar of intrinsically disordered protein phase separation.
• The discovered principles may have broad applicability in understanding cellular organization.