Biomolecular condensates undergo a generic shear-mediated liquid-to-solid transition


Membrane-less organelles resulting from liquid–liquid phase separation of biopolymers into intracellular condensates control essential biological functions, including messenger RNA processing, cell signalling and embryogenesis1,2,3,4. It has recently been discovered that several such protein condensates can undergo a further irreversible phase transition, forming solid nanoscale aggregates associated with neurodegenerative disease5,6,7. While the irreversible gelation of protein condensates is generally related to malfunction and disease, one case where the liquid-to-solid transition of protein condensates is functional, however, is that of silk spinning8,9. The formation of silk fibrils is largely driven by shear, yet it is not known what factors control the pathological gelation of functional condensates. Here we demonstrate that four proteins and one peptide system, with no function associated with fibre formation, have a strong propensity to undergo a liquid-to-solid transition when exposed to even low levels of mechanical shear once present in their liquid–liquid phase separated form. Using microfluidics to control the application of shear, we generated fibres from single-protein condensates and characterized their structural and material properties as a function of shear stress. Our results reveal generic backbone–backbone hydrogen bonding constraints as a determining factor in governing this transition. These observations suggest that shear can play an important role in the irreversible liquid-to-solid transition of protein condensates, shed light on the role of physical factors in driving this transition in protein aggregation-related diseases and open a new route towards artificial shear responsive biomaterials.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Fibre formation from LLPS proteins and peptides as a result of shear.
Fig. 2: Structural changes in FUS droplets following application of mechanical shear.
Fig. 3: Shear-mediated fibre formation probed by microfluidics.
Fig. 4: Material properties of fibres and proposed model of fibre formation from protein condensates under shear.

Data availability

All relevant data are included in the manuscript and Supplementary Information. More detailed protocols, calculation and analysis are available from the authors upon request.


  1. 1.

    Brangwynne, C. P. et al. Germline P granules are liquid droplets that localize by controlled dissolution/condensation. Science 324, 1729–1732 (2009).

    CAS  Google Scholar 

  2. 2.

    Wippich, F. et al. Dual specificity kinase DYRK3 couples stress granule condensation/dissolution to MTORC1 signaling. Cell 152, 791–805 (2013).

    CAS  Google Scholar 

  3. 3.

    Strzelecka, M. et al. Coilin-dependent SnRNP assembly is essential for zebrafish embryogenesis. Nat. Struct. Mol. Biol. 17, 403–409 (2010).

    CAS  Google Scholar 

  4. 4.

    Patel, A. et al. A liquid-to-solid phase transition of the ALS protein FUS accelerated by disease mutation. Cell 162, 1066–1077 (2015).

    CAS  Google Scholar 

  5. 5.

    Murakami, T. et al. ALS/FTD mutation-induced phase transition of FUS liquid droplets and reversible hydrogels into irreversible hydrogels impairs RNP granule function. Neuron 88, 678–690 (2015).

    CAS  Google Scholar 

  6. 6.

    Qamar, S. et al. FUS phase separation is modulated by a molecular chaperone and methylation of arginine cation-π interactions. Cell 173, 720–734 (2018).

    CAS  Google Scholar 

  7. 7.

    Jin, H.-J. & Kaplan, D. L. Mechanism of silk processing in insects and spiders. Nature 424, 1057–1061 (2003).

    CAS  Google Scholar 

  8. 8.

    Heim, M., Keerl, D. & Scheibel, T. Spider silk: from soluble protein to extraordinary fiber. Angew. Chem. Int. Ed. Engl. 48, 3584–3596 (2009).

    CAS  Google Scholar 

  9. 9.

    de Kruif, C. G., Weinbreck, F. & de Vries, R. Complex coacervation of proteins and anionic polysaccharides. Curr. Opin. Colloid Interface Sci. 9, 340–349 (2004).

    Google Scholar 

  10. 10.

    Ianiro, A. et al. Liquid–liquid phase separation during amphiphilic self-assembly. Nat. Chem. 11, 320–328 (2019).

    CAS  Google Scholar 

  11. 11.

    Vollrath, F., Porter, D. & Holland, C. The science of silks. MRS Bull. 38, 73–80 (2013).

    CAS  Google Scholar 

  12. 12.

    Holland, C., Vollrath, F., Ryan, A. J. & Mykhaylyk, O. O. Silk and synthetic polymers: reconciling 100 degrees of separation. Adv. Mater. 24, 105–109 (2012).

    CAS  Google Scholar 

  13. 13.

    Vollrath, F. & Knight, D. P. Liquid crystalline spinning of spider silk. Nature 410, 541–548 (2001).

    CAS  Google Scholar 

  14. 14.

    Weber, S. C. & Brangwynne, C. P. Getting RNA and protein in phase. Cell 149, 1188–1191 (2012).

    CAS  Google Scholar 

  15. 15.

    Shin, Y. & Brangwynne, C. P. Liquid phase condensation in cell physiology and disease. Science 357, eaaf4382 (2017).

    Google Scholar 

  16. 16.

    Yuan, C. et al. Nucleation and growth of amino acid and peptide supramolecular polymers through liquid–liquid phase separation. Angew. Chem. Int. Ed. Engl. 131, 18284–18291 (2019).

    Google Scholar 

  17. 17.

    Iserman, C. et al. Condensation of Ded1p promotes a translational switch from housekeeping to stress protein production. Cell 181, 818–831 (2020).

    CAS  Google Scholar 

  18. 18.

    Liao, Y.-C. et al. RNA granules hitchhike on lysosomes for long-distance transport, using annexin A11 as a molecular tether. Cell 179, 147–164 (2019).

    CAS  Google Scholar 

  19. 19.

    Ruggeri, F. S. et al. Infrared nanospectroscopy characterization of oligomeric and fibrillar aggregates during amyloid formation. Nat. Commun. 6, 1–9 (2015).

    Google Scholar 

  20. 20.

    Ruggeri, F. et al. Identification of oxidative stress in red blood cells with nanoscale chemical resolution by infrared nanospectroscopy. Int. J. Mol. Sci. 19, 2582 (2018).

    Google Scholar 

  21. 21.

    Ruggeri, F. S. et al. Concentration-dependent and surface-assisted self-assembly properties of a bioactive estrogen receptor α-derived peptide. J. Pept. Sci. 21, 95–104 (2015).

    CAS  Google Scholar 

  22. 22.

    Boeynaems, S. et al. Phase separation of C9orf72 dipeptide repeats perturbs stress granule dynamics. Mol. Cell 65, 1044–1055 (2017).

    CAS  Google Scholar 

  23. 23.

    Ke, H. et al. Shear-induced assembly of a transient yet highly stretchable hydrogel based on pseudopolyrotaxanes. Nat. Chem. 11, 470–477 (2019).

    CAS  Google Scholar 

  24. 24.

    Zebrowski, J., Prasad, V., Zhang, W., Walker, L. & Weitz, D. Shake-Gels: shear-induced gelation of laponite–PEO mixtures. Colloids Surf. A 213, 189–197 (2003).

    CAS  Google Scholar 

  25. 25.

    Axelrod, D., Koppel, D. E., Schlessinger, J., Elson, E. & Webb, W. W. Mobility measurement by analysis of fluorescence photobleaching recovery kinetics. Biophys. J. 16, 1055–1069 (1976).

    Google Scholar 

  26. 26.

    Niwayama, R. et al. Bayesian inference of forces causing cytoplasmic streaming in Caenorhabditis elegans embryos and mouse oocytes. PLoS ONE 11, e0159917 (2016).

    Google Scholar 

  27. 27.

    Goldstein, R. E. & van de Meent, J.-W. A physical perspective on cytoplasmic streaming. Interface Focus 5, 20150030 (2015).

    Google Scholar 

  28. 28.

    Brown, A. Axonal transport of membranous and nonmembranous cargoes: a unified perspective. J. Cell Biol. 160, 817–821 (2003).

    CAS  Google Scholar 

  29. 29.

    Brown, A. Slow axonal transport: stop and go traffic in the axon. Nat. Rev. Mol. Cell Biol. 1, 153–156 (2000).

    CAS  Google Scholar 

  30. 30.

    Kaether, C., Skehel, P. & Dotti, C. G. Axonal membrane proteins are transported in distinct carriers: a two-color video microscopy study in cultured hippocampal neurons. Mol. Biol. Cell 11, 1213–1224 (2000).

    CAS  Google Scholar 

  31. 31.

    Ochs, S. Fast axoplasmic transport of materials in mammalian nerve and its integrative role. Ann. N. Y. Acad. Sci. 193, 43–58 (1972).

    CAS  Google Scholar 

  32. 32.

    Roy, S., Zhang, B., Lee, V. M.-Y. & Trojanowski, J. Q. Axonal transport defects: a common theme in neurodegenerative diseases. Acta Neuropathol. 109, 5–13 (2005).

    Google Scholar 

  33. 33.

    Li, X. et al. 3D culture of chondrocytes in gelatin hydrogels with different stiffness. Polymers (Basel). 8, 269 (2016).

    Google Scholar 

  34. 34.

    Vigolo, D., Ramakrishna, S. N. & deMello, A. J. Facile tuning of the mechanical properties of a biocompatible soft material. Sci. Rep. 9, 7125 (2019).

    Google Scholar 

  35. 35.

    Chao, P.-H. G. et al. Silk hydrogel for cartilage. J. Biomed. Mater. Res. B 95B, 84–90 (2010).

    CAS  Google Scholar 

  36. 36.

    Partlow, B. P. et al. Highly tunable elastomeric silk biomaterials. Adv. Funct. Mater. 24, 4615–4624 (2014).

    CAS  Google Scholar 

  37. 37.

    Ashby, M. F., Gibson, L. J., Wegst, U. & Olive, R. The mechanical properties of natural materials. I. Material property charts. Proc. R. Soc. A 450, 123–140 (1995).

    Google Scholar 

  38. 38.

    Knowles, T. P. J. & Buehler, M. J. Nanomechanics of functional and pathological amyloid materials. Nat. Nanotechnol. 6, 469–479 (2011).

    CAS  Google Scholar 

  39. 39.

    Rockwood, D. N. et al. Materials fabrication from bombyx mori silk fibroin. Nat. Protoc. 6, 1612–1631 (2011).

    CAS  Google Scholar 

  40. 40.

    Ruggeri, F. S., Šneideris, T., Chia, S., Vendruscolo, M. & Knowles, T. P. J. Characterizing individual protein aggregates by infrared nanospectroscopy and atomic force microscopy. J. Vis. Exp. 12, e60108 (2019).

    Google Scholar 

  41. 41.

    Müller, J. et al. High-resolution CMOS MEA platform to study neurons at subcellular, cellular, and network levels. Lab Chip 15, 2767–2780 (2015).

    Google Scholar 

  42. 42.

    Ruggeri, F. S. et al. Nanoscale studies link amyloid maturity with polyglutamine diseases onset. Sci. Rep. 6, 31155 (2016).

    CAS  Google Scholar 

  43. 43.

    Shimanovich, U. et al. Silk micrococoons for protein stabilisation and molecular encapsulation. Nat. Commun. 8, 1–9 (2017).

    Google Scholar 

  44. 44.

    Yang, H. & Wang, K. Genomic variant annotation and prioritization with ANNOVAR and WANNOVAR. Nat. Protoc. 10, 1556–1566 (2015).

    CAS  Google Scholar 

  45. 45.

    Xia, Y. & Whitesides, G. M. Soft lithography. Annu. Rev. Mater. Sci. 28, 153–184 (1998).

  46. 46.

    Levin, A. et al. Ostwald’s rule of stages governs structural transitions and morphology of dipeptide supramolecular polymers. Nat. Commun. 5, 5219 (2014).

    CAS  Google Scholar 

Download references


This work is supported by the Welcome Trust, ERC, Alzheimer Association Zenith, ALS Canada–Brain Canada, Canadian Institutes of Health Research and the Cambridge Centre for Misfolding Diseases. We thank S. Zhang, Y. Lu and K.L. Saar for assistance with the design and fabrication of the microfluidic devices; K.H. Muller for help with flash-freezing and SEM imaging; and A. Alexiadis for discussions regarding fluid mechanics calculations.

Author information




Y.S. and T.P.J.K. conceived and designed the study. Y.S., F.S.R., A.K. and A.L. performed the experiments. Y.S., S.Q., P.S.G.-H., C.I., S.A. and A.K. produced the materials. F.S.R. performed AMF-IR and analysed the data. D.V. simulated the flow field. Y.S. imaged samples under SEM and ran microfluidic experiments and FRAP analysis. A.K. performed tensile strength measurements. Y.S., F.S.R., D.V., A.K. P.S.G.-H., S.A. and T.P.J.K. analysed the data. All authors contributed to the writing of the manuscript.

Corresponding author

Correspondence to Tuomas P. J. Knowles.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Figs. 1–5, Table 1, Movie descriptions and refs. 1–5.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Shen, Y., Ruggeri, F.S., Vigolo, D. et al. Biomolecular condensates undergo a generic shear-mediated liquid-to-solid transition. Nat. Nanotechnol. (2020).

Download citation