Mechanoresponsive lipid-protein nanoglobules facilitate reversible fibre formation in velvet worm slime

Alexander Baer,Georg Mayer,Michaela Eder,Sebastian Haensch,Matthew J Harrington,Stephan Schmidt

doi:10.1038/s41467-017-01142-x

Abstract

Velvet worms eject a fluid capture slime that can be mechanically drawn into stiff biopolymeric fibres. Remarkably, these fibres can be dissolved by extended exposure to water, and new regenerated fibres can be drawn from the dissolved fibre solution—indicating a fully recyclable process. Here, we perform a multiscale structural and compositional investigation of this reversible fabrication process with the velvet worm Euperipatoides rowelli, revealing that biopolymeric fibre assembly is facilitated via mono-disperse lipid-protein nanoglobules. Shear forces cause nanoglobules to self-assemble into nano- and microfibrils, which can be drawn into macroscopic fibres with a protein-enriched core and lipid-rich coating. Fibre dissolution in water leads to re-formation of nanoglobules, suggesting that this dynamic supramolecular assembly of mechanoresponsive protein-building blocks is mediated by reversible non-covalent interactions. These findings offer important mechanistic insights into the role of mechanochemical processes in bio-fibre formation, providing potential avenues for sustainable material fabrication processes.

Highlights

Velvet worms eject a fluid capture slime that can be mechanically drawn into stiff biopolymeric fibres
Recent biochemical studies performed on two onychophoran species from the genus Euperipatoides indicate that their capture slime is composed primarily of large unstructured proteins and several fatty acid variants, with smaller amounts of protein-bound carbohydrates and free amino acids[11,12,13] The ability to form fibres outside the body from extracted slime[11, 12] clearly indicates that the mechanism for fibre assembly must be encoded in these biomolecular building blocks, independent of biological input
Slime manually collected from the velvet worm species Euperipatoides rowelli is fluid-like at rest, but when agitated, forms sticky fibres that cure and stiffen through drying, losing their adhesiveness through the process (Fig. 1b, c) as previously reported for other species[17, 18]

Summary

Introduction

Velvet worms eject a fluid capture slime that can be mechanically drawn into stiff biopolymeric fibres. Slime manually collected from the velvet worm species Euperipatoides rowelli is fluid-like at rest, but when agitated, forms sticky fibres that cure and stiffen through drying, losing their adhesiveness through the process (Fig. 1b, c) as previously reported for other species[17, 18].

Results

Conclusion