Over 400 million years spiders have evolved to produce six different silks. Spider silks are comprised almost entirely of protein and are used for a diverse range of applications such as web construction, egg case production and wrapping prey. The silks vary dramatically in their mechanical and physical properties with the major ampullate silk (dragline) exhibiting a strength that exceeds steel by weight and a toughness greater than Kevlar while, the flagelliform silk has extensibility comparable to rubber. Our lab is focused on understanding the molecular structure and dynamics of the proteins that comprise the various spider silk fibers. It is the folded structures and hierarchical organization of these proteins that imparts spider silks their impressive yet, diverse mechanical and physical properties. Our research team has been developing and applying a suite of solution, diffusion and solid-state NMR techniques to probe secondary structure (see Figure 1), hydrogen-bonding, side chain dynamics, and oligomeric protein assembly all of which are crucial to understanding spider silk formation and the resulting fiber properties. Recently, we have focused on understanding the protein-rich fluid within the various silk producing glands to determine the conformational structure and dynamics prior to fiber formation and elucidate the important biochemical triggers responsible for converting the gel-like liquid to fibers with unparalleled properties. Insights into the state of the protein in the gland are being gained from a combination of diffusion NMR and cryo-electron microscopy (EM) that is providing evidence for supramolecular silk protein organization prior to fiber spinning. It is our belief that a better fundamental understanding of the spider silk protein molecular structure and assembly process will accelerate the ability to mimic and reproduce similar biologically inspired fibers in the laboratory.

Using NMR to probe the structure, dynamics and assembly of spider silk fibers

255th National Meeting (2018)

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