Structural venomics reveals evolution of a complex venom by duplication and diversification of an ancient peptide-encoding gene

Spiders are the most successful venomous animals on the planet, with more than 48,000 described species. Most spider venoms are dominated by disulfide-rich peptides (DRPs) with a diverse range of pharmacological activities. Some spider venoms contain thousands of unique peptides, but little is known about the mechanisms used to generate such complex chemical arsenals. We used an integrated transcriptomic, proteomic, and structural biology approach to demonstrate that the lethal Australian funnel-web spider produces 33 superfamilies of venom peptides and proteins, more than described for any other venomous animal. 26 of the 33 superfamilies are DRPs, and we show that 15 of these are knottins that contribute >90% of the venom proteome.