Spider Silk and Amyloid Fibrils: A Structural Comparison

Abstract

Although spider silks have been studied for decades, the assembly properties of the underlying silk proteins have still not been unravelled. Previously, the detection of amyloid-like nanofibrils in the spider's silk gland suggested their involvement in the assembly process.Recombinantly produced spider silk also self-assembles into nanofibrils. In order to investigate the structural properties of such silk nanofibrils in more detail, they have been compared to amyloid-like fibrils to highlight structural similarities.

The elaborate structure of spider silk

“…63,64 This particular system benefits from the fact that the In vitro spider silk is further able to self-assemble into small nanofibrils upon incubation in potassium phosphate buffer for several days at room temperature. 74,75 The resulting fibrils are structurally comparable to amyloid fibrils.…”

Assembly mechanism of recombinant spider silk proteins

“…Producing engineered spider silk proteins recombinantly in bacteria provides, however, new possibilities for the investigation of spinning processes (5)(6)(7). In this work, we used eADF3 and eADF4, previously established engineered variants of the dragline silk fibroins ADF3 and ADF4 of the garden spider Araneus diadematus (8).…”

“…S1 and Materials and Methods]. Under distinct solvent conditions these engineered silk proteins controllably assemble into different morphologies, such as nanofibrils (6), hydrogels (7), films (9,10), and microcapsules (11). Further, conditions for a liquidliquid phase separation have been identified, leading to large colloidal assemblies that likely reflect a prerequisite for silk fiber formation (12).…”

Specific Chaperones and Regulatory Domains in Control of Amyloid Formation

“…Electron microscopy additionally suggests that yeast prion fibers are capable of forming higher-order structures linked by organizational elements (5). Spider silk, which shares key characteristics with amyloid fibers (6,7), is composed of ␤-crystalline blocks connected by unstructured segments, an architecture that gives rise to the exceptional properties of silk (8 -10).…”