Motif-pattern dependence of biomolecular phase separation driven by specific interactions.

Area of Science:

• Biochemistry
• Cell Biology
• Polymer Physics

Background:

• Eukaryotic cells utilize membrane-less biomolecular condensates for compartmentalization.
• Phase separation drives condensate formation, influenced by both non-specific and specific molecular interactions.
• The precise rules governing how specific binding motifs drive phase separation remain incompletely understood.

Purpose of the Study:

• To elucidate the role of specific binding motif sequences in driving polymer phase separation.
• To understand how sequence affects biomolecular condensate properties like viscosity and diffusion.
• To identify the underlying physical mechanisms by which sequence controls phase separation.

Main Methods:

• Integration of Monte Carlo simulations for lattice-polymers.
• Application of mean-field theory.
• Analysis of polymer conformational entropy and inter-polymer bonding.

Main Results:

• Polymer sequence significantly impacts phase separation boundaries and condensate properties.
• Sequences with large blocks of single motifs enhance inter-polymer bonding and promote phase separation.
• Sequence primarily influences phase separation by modulating the conformational entropy of self-bonding.

Conclusions:

• The sequence of specific binding motifs is a critical determinant of polymer phase separation.
• An entropy-based mechanism, rather than solely energy-based, governs sequence-driven phase separation.
• This finding offers new insights into the biological regulation of biomolecular condensates.