Dresden 2020 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 47: Focus: Phase Separation in Biological Systems II (joint session BP/CPP)

CPP 47.2: Talk

Tuesday, March 17, 2020, 09:45–10:00, ZEU 250

Protein condenstates as aging Maxwell fluids — •Louise Jawerth¹, Elisabeth Fischer-Friedrich², Anthony Hyman³, and Frank Julicher¹ — ¹Max Planck Institute for the Physics of Complex Systems — ²Biotec, TU Dresden, Tatzberg 47-49, 01307 Dresden, Germany — ³Max Planck Institute of Molecular Cell Biology and Genetics

Protein condensates (PC) are intracellular compartments that segregate material without the use of a membrane. The liquid-like behavior of the condensates is a defining characteristic and the material properties of condensates are tuned to their biological function. It has become increasingly clear that some condensates do not have time-independent material properties, but can, instead, transition to more solid, gel-like materials. Here, we present our efforts to quantify these new materials as they age in vitro. We measure the visco-elastic material properties of several proteins by means of a combination of active and passive microrheology. At early times, we find that the droplets behave much like simple liquids but gradually become more elastic. Surprisingly, the changing mechanical properties can all be scaled onto a single master curve using one characteristic time scale which grows as the sample ages. We consider protein condensates as soft glassy materials with age dependent material properties that we call Maxwell glasses. To gain insight into the molecular origins of this behavior, we present electron microscopy images of the condensates at different ages. Furthermore, we demonstrate how salt concentration tunes the characteristics of the aging process.