Chemical and Biological Physics Dept Seminar
Date:
Lecture / Seminar
Time: 10:00-11:00
Title: Liquid phase separation of proteins controlled by pH
Location: Helen and Milton A. Kimmelman Building
Lecturer: Dr. Omar Arana
Organizer: Department of Chemical and Biological Physics
Details: Liquid phase separation of proteins controlled by pH
Abstract: In the past decade, liquid phase separation has been proposed as a mechanism for ... Read more In the past decade, liquid phase separation has been proposed as a mechanism for intracellular
organization. It has been shown that many proteins phase-separate and form liquid-like drops. These liquid-like compartments provide a distinct biochemical environment inside of the cell and sometimes form as a response to changes in the intracellular environment. In particular, a decrease in the pH of the cytosol of yeast cells leads to widespread macromolecular assembly. Inspired by this experimental observation, we construct a minimal model to study this
pH-responsive mechanism. The model consists of a macromolecular mixture in which macromolecules can exist in different charge states and have a tendency to phase-separate. In order to assess the effect of pH on phase separation, we introduce protonation and deprotonation reactions, which are controlled by the pH of the mixture. Using this model, we construct phase diagrams at the isoelectric point of the system and then study what happens when the pH is moved away from the isoelectric point. We find that under most conditions, the broadest region of phase separation is located at the isoelectric point. Interestingly, our minimal model also predicts reentrant behavior as a function of pH. We conclude by discussing the predictions of our model in light of experimental observations on protein phase separation, showing that they are in agreement.
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