Speaker: Patrick McCall, Independent Research Associate, Division of Polymer Biomaterials Science, Max Bergmann Center, Leibniz Institute of Polymer Research Dresden

Title: “Contrasting phases: from biomolecular composition to condensate properties and functionality”

Date: Tuesday, 05 May 2026

Time: 12:00

Room: Left Auditorium, CRTD, Fetscherstrasse 105, 01307 Dresden

Host: Research Training Group Biomolecular Condensates (RTG 3120)

Abstract: Biomolecular condensates are dense phases enriched in specific molecules and their complex composition underlies their physical properties as well as their contribution to essential physiological processes. Reconstitution of minimal model systems from purified components is a powerful tool to handle this complexity but doesn’t provide control of local composition directly, as a condensate’s composition is itself an emergent property governed by a complex mix of entropic effects and molecular interactions. The loss of compositional control upon phase separation is most acute in multicomponent systems, as the local component stoichiometry need not reflect the average specified by an experimenter.

In this talk, I will describe how the composition of multicomponent condensates can be measured using a label-free method we developed recently based on the analysis of tie-lines and refractive index (ATRI). I will show how precise compositional measurements across a range of model systems reveal sequence-encoded variation in physical properties for RNA-binding protein (RBP) condensates, a decoupling transition between local RNA/RBP stoichiometry and density, and how local density can regulate enzymatic reactions in peptide/ribozyme condensates. Finally, I will also discuss how couplings between distinct aspects of composition, from density and stoichiometry to local charge content and pH, provide a useful basis for contrasting condensate microenvironments and potentially for interpreting their functional consequences for regulating biochemistry.