Elucidation and mimicry of velvet worm slime fiber formation: Towards sustainable polymer fabrication
Final Report Abstract
The slime of velvet worms (Onychophora) provides an example of naturally synthetized recyclable, protein-based polymers. The building blocks of fibers are stored in an aqueous solution and react instantly to compression and shear forces by cross linking into a gel, which can be drawn into tough fibers. Chemical bonds between the components are non-covalent, as the gel dissociates in water after minutes and the fibers within hours. The components can thus be recovered in water and reused to form fibers. The mentioned processes take place outside the organism and are independent from the regulatory processes within the gland. The formation of the fiber is therefore a selfregulatory process from liquid to solid, which is induces merely by a mechanical trigger. The underlying physico-chemical principles were therefore investigated in detail for potential future biotechnological applications. In the conducted subprojects, (i) the spatial distribution of proteins and lipids was elucidated; (ii) a phosphonate-carbohydrate compound was identified, which is rare among terrestrial organisms and influences the properties of fiber-forming proteins in velvet worms; and (iii) the sequences of essential proteins were decoded, the chemical structures and post-translational modifications of which are conserved across the three onychophoran species studied. The major findings, which have been published in renowned journals and well received by the scientific community, challenge the previous model on the function of the onychophoran slime. Not only electrostatic interactions between oppositely charged regions and modifications of proteins, but also hydrophobic interactions serve their aggregation and increase their stability. The spatial separation of proteins with different properties is used for storage and prevents premature aggregation. The findings demonstrate that distinct domains of the essential proteins contribute to diverse properties and functions, which must be considered in response to different requirements in nature for adhesion to a variety of surfaces, rapid formation, and stability of fibers. A step-by-step reproduction of components and testing their properties now appears possible. It represents the first step towards new ways of synthesizing sustainable biological polymers and materials.
Publications
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Peculiar Phosphonate Modifications of Velvet Worm Slime Revealed by Advanced Nuclear Magnetic Resonance and Mass Spectrometry. Journal of the American Chemical Society, 145(38), 20749-20754.
Poulhazan, Alexandre; Baer, Alexander; Daliaho, Gagan; Mentink-Vigier, Frederic; Arnold, Alexandre A.; Browne, Darren C.; Hering, Lars; Archer-Hartmann, Stephanie; Pepi, Lauren E.; Azadi, Parastoo; Schmidt, Stephan; Mayer, Georg; Marcotte, Isabelle & Harrington, Matthew J.
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The Internal Structure of the Velvet Worm Projectile Slime: A Small‐Angle Scattering Study. Small, 19(22).
Baer, Alexander; Hoffmann, Ingo; Mahmoudi, Najet; Poulhazan, Alexandre; Harrington, Matthew J.; Mayer, Georg; Schmidt, Stephan & Schneck, Emanuel
