With this award, the Chemistry of Life Processes Program in the Chemistry Division is supporting a collaborative project between Dr. Matthew Cordes at the University of Arizona and Dr. Greta Binford at Lewis and Clark College, to determine how spider venom toxins target and destroy different molecules on cell surfaces. Venoms of brown recluse spiders have toxins that cause the death of cells and tissue in mammals, but also help the spiders immobilize and/or digest insect prey. The toxins that are known to affect mammals can damage cell surfaces by cutting a specific "head group", called choline, off of a molecule called a sphingolipid. Other recluse spider toxins can only cut off a different kind of head group, called ethanolamine, that mammals do not have in their sphingolipids, so these toxins may be less harmful to mammals. Many insects have both kinds of head group, so both types of toxin are probably important for predation, perhaps in different ways. Dr. Cordes, a structural biologist and biochemist, and Dr. Binford, a biologist and expert on venomous invertebrates, combine their expertise to determine how these toxins distinguish the different head groups, and what the biological consequences are for predators and their prey. The specific action of these toxins on different head groups could also make them useful in biotechnology for detecting or manipulating different kinds of cell surfaces. The broader impacts of this project involve outreach through mentorship of undergraduates doing integrative and collaborative research at two different institutions. Spiders attract public interest and afford an opportunity to inform the public on scientific investigations on the subject. An innovative program known as "SpiderFest" is conduucted both at the laboratory and at a science expo in Portland.
The overall goal of this project is to understand the causes and effects of substrate head group (ethanolamine vs. choline) preference in phospholipase D toxins from recluse spiders. The specific goals are to map interfacial binding sites in the toxins, elucidate amino-acid sequence determinants of substrate head group preference; characterize the evolution of substrate preference in the recluse spider toxin family; and correlate head group preference to biological effects of the toxins. Methods to be used include NMR, X-ray crystallography, computational structural biology, site-directed mutagenesis, phylogenetic reconstruction, enzymatic assays, and biological assays. Information from this study illuminates differential recognition, by proteins that act at membrane surfaces, of the two most common lipid head groups in nature, phosphocholine and phosphoethanolamine. The project also sheds light on toxin recruitment and specialization in venoms and interesting aspects of arthropod biochemistry and neurobiology. These toxins could also be developed into valuable analytical tools to probe important differences in cell surface structure.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
