Journal Article

Thermodynamics of wetting, prewetting and surface phase transitions with surface binding

Jülicher, Frank, Zhao, Xueping, Weber, Christoph A, Honigmann, Alf, Bartolucci, Giacomo

2021

Overview

In living cells, protein-rich condensates can wet the cell membrane and surfaces of membrane-bound organelles. Interestingly, many phase-separating proteins also bind to membranes leading to a molecular layer of bound molecules. Here we investigate how binding to membranes affects wetting, prewetting and surface phase transitions. We derive a thermodynamic theory for a three-dimensional bulk in the presence of a two-dimensional, flat membrane. At phase coexistence, we find that membrane binding facilitates complete wetting and thus lowers the wetting angle. Moreover, below the saturation concentration, binding facilitates the formation of a thick layer at the membrane and thereby shifts the prewetting phase transition far below the saturation concentration. The distinction between bound and unbound molecules near the surface leads to a large variety of surface states and complex surface phase diagrams with a rich topology of phase transitions. Our work suggests that surface phase transitions combined with molecular binding represent a versatile mechanism to control the formation of protein-rich domains at intra-cellular surfaces.

• Publisher: IOP Publishing
• Subject: Binding / Cell membranes / Organelles / Phase diagrams / Phase transitions / Physics / Proteins / Saturation / surface binding / surface phase transitions / thermodynamics of wetting and prewetting / Topology / Wetting