Liquid-liquid crystalline phase separation of spider silk proteins

Abstract

Liquid-liquid phase separation (LLPS) of proteins can be considered an intermediate solubility regime between disperse solutions and solid fibers. While LLPS has been described for several pathogenic amyloids, recent evidence suggests that it is similarly relevant for functional amyloids. Here, we review the evidence that links spider silk proteins (spidroins) and LLPS and its role in the spinning process. Major ampullate spidroins undergo LLPS mediated by stickers and spacers in their repeat regions. During spinning, the spidroins droplets shift from liquid to crystalline states. Shear force, altered ion composition, and pH changes cause micelle-like spidroin assemblies to form an increasingly ordered liquid-crystalline phase. Interactions between polyalanine regions in the repeat regions ultimately yield the characteristic beta-crystalline structure of mature dragline silk fibers. Based on these findings, we hypothesize that liquid-liquid crystalline phase separation (LLCPS) can describe the molecular and macroscopic features of the phase transitions of major ampullate spidroins during spinning and speculate whether other silk types may use a similar mechanism to convert from liquid dope to solid fiber.Liquid-liquid phase separation (LLPS) of proteins can be considered an intermediate solubility regime between disperse solutions and solid fibers, relevant to both pathogenic and functional amyloids. Here, the authors review the evidence that links spider silk proteins (spidroins) and LLPS and its role in the spinning process.

Published in

Communications Chemistry
2024, volume: 7, number: 1, article number: 260
Publisher: NATURE PORTFOLIO

SLU Authors

• Rising, Anna

  • Department of Animal Biosciences, Swedish University of Agricultural Sciences
    
  • Karolinska Institute

UKÄ Subject classification

Paper, Pulp and Fiber Technology
Physical Chemistry

Publication identifier

• DOI: https://doi.org/10.1038/s42004-024-01357-2

Permanent link to this page (URI)

https://res.slu.se/id/publ/139352