Biomolecular Condensates Formed by Designer Minimalistic Peptides

Inspired by the role of intracellular liquid-liquid phase separation (LLPS) in formation of membraneless organelles, there is great interest in developing dynamic compartments formed by LLPS of intrinsically disordered proteins (IDPs) or short peptides. However, the molecular mechanisms underlying the formation of such biomolecular condensates have not been fully elucidated, rendering on-demand design of synthetic condensates with tailored physico-chemical functionalities and responsiveness to specific stimuli a significant challenge. To address this need we have designed a library of LLPS-promoting peptide building blocks composed of various assembly domains. We show that the LLPS propensity, dynamics, and encapsulation efficiency of compartments can be tuned by specific changes to the peptide composition at the single amino acids level, with Raman and NMR spectroscopy proving instrumental in determining the molecular contribution of each side chain to droplet formation. The resulting sequence-structure-function correlation is mandatory for future development of compartments for a variety of applications.