Regensburg 2025 – scientific programme

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BP: Fachverband Biologische Physik

BP 14: Poster Session I

BP 14.18: Poster

Tuesday, March 18, 2025, 10:00–12:30, P3

Theory of spatial aggregation and shell formation — •Pranay Jaiswal, Ivar Haugerud, and Christoph Weber — Institute of Physics, University of Augsburg, Augsburg, Germany

Many biological systems use coexisting phases composed of proteins and RNA to regulate chemical processes and molecular transport. In particular, the interface can act as a nucleation site for aggregation of proteins, leading to the formation of a solid-like shell. This shell provides a physical barrier for molecular transport of further biomolecules, giving rise to molecule-specific interface permeabilities. Here we propose a theoretical model for spatio-temporal protein aggregation in phase-separated systems. To this end, we use a phase-field of proteins and RNA combined with a phase-field characterising the solid-like, aggregated state. Our key finding is that aggregation is thermodynamically favored at the interface, making aggregation shells a likely phenomenon in phase-separated systems of aggregation-prone proteins. We show how such aggregation shells control molecular transport and shell permeabilities. Our theory can be applied to experimental systems undergoing irreversible aggregation to unravel the molecular mechanism underlying ageing in protein mixtures.

Keywords: aggregation; biocondensates; ageing proteins; permeabilities; spatio-temporal phase field