Phase Separation and Ageing of Glycine-Rich Protein from Tick Adhesive

Ganar, K. A.; Turbina, P.; Nandy, M.; Chen, C.; Suylen, D.; van der Beelen, S.; Pascoe, E. L.; Koenraadt, C. J. M.; Dijkgraaf, I.; Deshpande, S.

doi:10.1101/2023.03.27.534361

bioRxiv · 10.1101/2023.03.27.534361

Phase Separation and Ageing of Glycine-Rich Protein from Tick Adhesive

Ganar, K. A.·Turbina, P.·Nandy, M.·Chen, C.·Suylen, D.·van der Beelen, S.·Pascoe, E. L.·Koenraadt, C. J. M.·Dijkgraaf, I.·Deshpande, S.

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Abstract

Hard ticks feed on their host for multiple days. To ensure firm attachment, they secrete a protein-rich saliva that eventually forms a solid cement cone. The underlying mechanism of this liquid-to-solid transition is not yet understood. This study focuses on the phase transitions of a disordered glycine-rich protein (GRP) that is prominent in tick saliva. We show that GRP undergoes liquid-liquid phase separation via simple coacervation to form biomolecular condensates in salty environments. Cation-pi and pi-pi interactions near the C-terminus promote coacervation while a negatively charged N-terminus prolongs its onset through electrostatic repulsion. Interestingly, GRP condensates exhibit ageing and undergo liquid-to-gel transition to form viscoelastic networks as well as solid-like condensates. Lastly, we provide evidence for protein-rich condensates in natural tick saliva. Our findings provide a starting point to gain insights into the bioadhesion of ticks, develop novel tick control strategies, and towards biomedical applications such as tissue sealants.

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Ganar, K. A., Turbina, P., Nandy, M., Chen, C., Suylen, D., van der Beelen, S., Pascoe, E. L., Koenraadt, C. J. M., Dijkgraaf, I., Deshpande, S.. 2023-03-27. Phase Separation and Ageing of Glycine-Rich Protein from Tick Adhesive. https://doi.org/10.1101/2023.03.27.534361

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