Pressure-Jump Kinetics of Liquid–Liquid Phase Separation: Comparison of Two Different Condensed Phases of the RNA-Binding Protein, Fused in Sarcoma

• DOI: 10.1021/jacs.1c07571
• Publication Date: 2021-11-17T14:46:27Z
• Authors: Ryo Kitahara; Ryota Yamazaki; Fumika Ide; Shujie Li; Yutaro Shiramasa; Naoya Sasahara; Takuya Yoshizawa
• Keywords: 0301 basic medicine; Kinetics; 03 medical and health sciences; Pressure; RNA-Binding Protein FUS; Protein Multimerization; Phase Transition

The RNA-binding protein fused in sarcoma (FUS) undergoes liquid–liquid phase separation (LLPS) both vivo and vitro. Self-assembled liquid droplets of FUS transform into reversible hydrogels more irreversible toxic aggregates. Although LLPS can be a precursor aggregates, generic method to study kinetics the formation has not been developed. Here, we demonstrated pressure-jump transition between 1-phase state FUS-LLPS states observed at low pressure (<2 kbar, LP-LLPS) high (>2 HP-LLPS) using high-pressure UV/vis spectroscopy. Absorbance (turbidity) changes were reproduced repeatedly cycles. Johnson–Mehl–Avrami–Kolmogorov theory was used understand droplet occurring via nucleation growth. Avrami exponent n, representing dimensionality growing droplets, reaction rate constant k calculated. HP-LLPS ∼2-fold slower than that LP-LLPS. obtained for could explained by diffusion-limited Nucleation growth rates decreased during LP-LLPS (n = 0.51), with 1.4). vanishing ∼20-fold This difference indicates stronger intermolecular interaction LP-LLPS, which might promote transformation aggregates droplets. Further, direct from observed. interconversion occurs equilibrium. Formation followed another phase, thus part physiological maturation process FUS-LLPS.