Nature Chemistry (2024). DOI: 10.1038/s41557-024-01686-8">
Researchers uncover the physical chemistry behind tick adhesion to skin
Glycine-rich protein present in tick saliva is intrinsically disordered and shows a high propensity for LLPS. Credit: Nature Chemistry (2024). DOI: 10.1038/s41557-024-01686-8
A team of physical chemists at Wageningen University and Research, Maastricht University and EnzyTag BV, all in the Netherlands, has uncovered the physical chemistry behind the ticks' ability to adhere to the skin of its host. In their study, published in the journal Nature Chemistry, the group observed the evaporation of a drop of artificially synthesized amino acid similar to the kind produced in tick saliva to see if it would show phase separation.
Prior research has shown that when a tick catches a ride on a passing host, it adheres, then pierces the skin and feeds. In this new study, the research team noted that the sticking mechanism has not previously been well studied. They began by collecting samples of the saliva protein produced by the ticks, which they noted formed into solid cones when extruded onto the skin of its host. That meant that it was a bio-adhesive, the only one known to stick to a living substrate.
They found that the tick saliva had glycine-rich proteins, which was due to the tick upping its production just prior to latching onto a host. Prior research has shown that such proteins can prevent protein folding, which accounts for the degree of hardness of the cone that forms.
In studying the tick saliva and its proteins, the team found evidence of a possible liquid-to-liquid phase separation. To confirm it, they created a synthetic version of one of the main amino acids found in the saliva and placed a drop on a flat surface and watched it evaporate.
Prior research has shown that other liquid-to-liquid phase separations, such as those that occur in coffee, result in the creation of rings as they dry. After a few minutes, the research team found the rings they were expecting—they also noted fluorescence at the ring boundary and the creation of a rim. Finally, they observed tiny droplets of the synthesized protein floating in the rim.
Taken together, the behavior of the drop showed that liquid-to-liquid phase separation. The addition of salt helped to strengthen the bonds in the fluid, resulting in harder cones. To confirm that the natural tick saliva exhibited phase separation, they captured enough ticks to extract a quantity of saliva sufficient to repeat the earlier work using real saliva and found the same results.
More information: Ketan A. Ganar et al, Phase separation and ageing of glycine-rich protein from tick adhesive, Nature Chemistry (2024). DOI: 10.1038/s41557-024-01686-8
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Citation: Researchers uncover the physical chemistry behind tick adhesion to skin (2024, December 9) retrieved 9 December 2024 from https://phys.org/news/2024-12-uncover-physical-chemistry-adhesion-skin.html
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