Chemistry Seminar with Dr. Yifan Dai from WashU BME at 4:00pm

Abstract: Phase transitions driven by multivalent biomacromolecules, such as intrinsically disordered proteins, have emerged as a critical organizational strategy in living cells. This transition process results forms membraneless structures known as biomolecular condensates. A key conundrum in condensate research is why such a second phase is necessary for cellular functions, as the same effects of sequestration, exclusion and enrichment generated by a phase separated condensate can also be achieved through the formation of stoichiometric macromolecular assemblies and the phase transition process is thermodynamically costly. In this talk, I will untangle this conundrum by presenting examples that illustrate how the phase transition of biomacromolecules leads to a density transition of the entire solution system (the cellular matrix), governed by electrochemical potential equilibrium. This transition process generates an ion density gradient between phases, encoding an electric potential gradient between phases. I will show how this process regulates cellular electrochemistry. I will further demonstrate how the formation of a second phase delivers electrochemically active surfaces, which can encode interfacial electric field that can power diverse chemical reactions. These inherent electrochemical functions of biological assemblies reveal a non-enzymatic strategy of living cells on modulating cellular chemical homeostasis, potentially leading to disease progression. Overall, our works present a new paradigm for understanding cellular functioning mechanisms and intracellular electrochemistry.