Journal Article

Liquid-Liquid Phase Separation of Patchy Particles Illuminates Diverse Effects of Regulatory Components on Protein Droplet Formation

Nguemaha, Valery, Zhou, Huan-Xiang

2018

Overview

Recently many cellular functions have been associated with membraneless organelles, or protein droplets, formed by liquid-liquid phase separation (LLPS). Proteins in these droplets often contain RNA-binding domains, but the effects of RNA on LLPS have been controversial. To gain better understanding on the roles of RNA and other macromolecular regulators, here we used Gibbs-ensemble simulations to determine phase diagrams of two-component patchy particles, as models for mixtures of proteins with regulatory components. Protein-like particles have four patches, with attraction strength ε PP ; regulatory particles experience mutual steric repulsion but have two attractive patches toward proteins, with the strength ε PR tunable. At low ε PR , the regulator, due to steric repulsion, preferentially partitions in the dispersed phase, thereby displacing the protein into the droplet phase and promoting LLPS. At moderate ε PR , the regulator starts to partition and displace the protein in the droplet phase, but only to weaken bonding networks and thereby suppress LLPS. At ε PR  >  ε PP , the enhanced bonding ability of the regulator initially promotes LLPS, but at higher amounts, the resulting displacement of the protein suppresses LLPS. These results illustrate how RNA can have disparate effects on LLPS, thus able to perform diverse functions in different organelles.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 119/118 / 631/57/2266 / 639/638/440/951 / DNA-Binding Proteins - chemistry / DNA-Binding Proteins - genetics / Humanities and Social Sciences / Intrinsically Disordered Proteins - chemistry / Intrinsically Disordered Proteins - genetics / Macromolecular Substances - chemistry / Macromolecular Substances - metabolism / Macromolecules / Membranes - chemistry / Membranes - metabolism / Models, Theoretical / multidisciplinary / Organelles / Organelles - chemistry / Organelles - genetics / Phase diagrams / Protein Biosynthesis - genetics / Protein Interaction Domains and Motifs - genetics / Protein Interaction Maps - genetics / Proteins / Proteins - chemistry / Proteins - genetics / Regulatory Sequences, Nucleic Acid - genetics / Ribonucleic acid / RNA / RNA - chemistry / RNA - genetics / RNA-Binding Motifs - genetics / Science / Science (multidisciplinary)