CBE & MSE Seminar: The Molecular Mechanisms of Spider Silk Assembly

Abstract: Over 300 million years, spiders have evolved to produce six different silks and one glue-like substance. 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 and a toughness greater than Kevlar while, the flagelliform silk has an elasticity 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 techniques including nuclear magnetic resonance (NMR), molecular dynamics (MD) simulations, synchrotron X-ray diffraction (XRD) and cryo-electron microscopy (cryo-EM) to probe secondary structure, hydrogen-bonding, side chain dynamics, nanocrystallinity 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 molecular structure and dynamics prior to fiber formation and elucidate the important biochemical triggers responsible for converting this gel-like liquid to fibers with unparalleled, yet diverse properties. 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 materials in the laboratory.

Bio: Gregory P. Holland was born in the borough of Queens, New York City. He attended the State University of New York at Buffalo where he received a bachelor's degree in chemistry in 1998. He moved on to the University of Wyoming where he graduated with a doctorate in physical and analytical chemistry in 2003. Holland then became a postdoctoral fellow at Sandia National Laboratories in the Laboratory of Todd Alam where he focused on NMR spectroscopy of biomolecules and nanomaterials. Following his postdoc, Holland served as a research professor in the Department of Chemistry and Biochemistry and Magnetic Resonance Research Center (MRRC) at Arizona State University (ASU). Holland still maintains strong connections and collaborations with the MRRC at ASU where he holds an adjunct professor position in the School of Molecular Sciences. In January 2015, Holland moved his research group to San Diego State University where he is an associate professor in the Department of Chemistry and Biochemistry. His lab continues to focus on the development and application of nuclear magnetic resonance for the characterization of biologically inspired materials, molecules and nanomaterials. Holland has won a number of awards for research and teaching, including a Kavli Fellowship in 2016 and the SDSU College of Sciences Outstanding Faculty Award in 2018.  

Host: Allon Hochbaum