Phase separation of multicomponent peptide mixtures into dehydrated clusters with hydrophilic cores

Biophys J. 2024 Jan 1:S0006-3495(23)04180-2. doi: 10.1016/j.bpj.2023.12.027. Online ahead of print.ABSTRACTPhase separation of biomolecules underlies the formation and regulation of various membraneless condensates in cells. How condensates function reliably while surrounded by heterogeneous and dynamic mixtures of biomolecular components with specific and non-specific interactions is yet to be understood. Studying multi-component biomolecular mixtures with designer peptides has recently become an attractive avenue for learning about physicochemical principles governing cellular condensates. In this work, we employed long timescale atomistic simulations of multi-component tripeptide mixtures with all residue substitutions to illuminate the nature of direct and water-mediated interactions in a prototypical cellular condensate environment. We find that peptide mixtures form clusters with inverse hydrophobic order. Most multivalent and charged residues are localized in the cluster's core, with a large fraction of non-aromatic hydrophobic residues remaining on the surface. This inverse hydrophobic order in peptide clusters is partly driven by the expulsion of non-specifically bound water molecules following peptide cluster growth. The growth of clusters is also accompanied by the formation of increasing numbers of specific water-mediated interactions between polar and charged residues. While the present study focused on the condensation of short peptide motifs, some general findi...
Source: Biophysical Journal - Category: Physics Authors: Source Type: research