Effect of Multivalency on Phase-Separated Droplets Consisting of Poly(PR) Dipeptide Repeats and RNA at the Solid/Liquid Interface

Abstract

Dipeptide repeat proteins (DRPs) are considered a significant cause of amyotrophic lateral sclerosis (ALS), and their liquid–liquid phase separation (LLPS) formation with other biological molecules has been studied both in vitro and in vivo. The immobilization and wetting of the LLPS droplets on glass surfaces are technically crucial for the measurement with optical microscopy. In this work, we characterized the surface diffusion of LLPS droplets of the DRPs with different lengths to investigate the multivalent effect on the interactions of their LLPS droplets with the glass surface. Using fluorescence microscopy and the single-particle tracking method, we observed that the large multivalency drastically changed the surface behavior of the droplets. The coalescence and wetting of the droplets were accelerated by increasing the multivalency of peptides in the LLPS system. Our findings on the effect of multivalency on interactions between droplets and glass surfaces could provide a new insight to enhance the understanding of LLPS formation and biophysical properties related to the solid/liquid interface.

The Effects of Dehydration Temperature and Monomer Chirality on Primitive Polyester Synthesis and Microdroplet Assembly

“…[23] This is partially due to their similarity in structure to modern membraneless organelles, which play diffusive, coalescence and wetting, pathological, and catalytic roles within cells, suggesting their longstanding importance to biology. [24][25][26] However, understanding of the scope of synthetic conditions which enable such prebiotic polyester and droplet formation is presently limited in scope, often using only the most experimentally expedient temperature conditions (e.g., 80 °C) [19,22] and starting materials (racemic 𝛼HA monomers). [19,22] It is thus of interest to explore a wider range of plausible early Earth conditions and reactant types that could lead to polyester polymerization and microdroplet assembly from them.…”

“…[ 23 ] This is partially due to their similarity in structure to modern membraneless organelles, which play diffusive, coalescence and wetting, pathological, and catalytic roles within cells, suggesting their longstanding importance to biology. [ 24–26 ]…”

Recent progress in primitive polyester synthesis and membraneless microdroplet assembly

“…Nevertheless, another possibility could be through macromolecular self-assembly, which was absolutely essential to the origins of life [54][55][56]. However, macromolecular self-assemblies could take many forms, for example droplets [57,58], crystals [59,60], fibers [61,62], or even more complex architectures [63,64]. However, one type of macromolecular selfassembly likely to have been relevant for origins of life were primitive compartments, also known as protocells, which themselves may have eventually evolved into modern cells (although it is not a strict requirement) [65][66][67].…”

Small Amphiphile‐Based Coacervation

“…Another mechanism is the passive coalescence of adjunction droplets through the Brownian motion [48] . In addition, the proliferating, division, diffusion and mobility on substrates were widely investigated [49–52] …”

“…[48] In addition, the proliferating, division, diffusion and mobility on substrates were widely investigated. [49][50][51][52]…”