Three-dimensional (3D) structures have been used to explore the evolution of proteins for decades, yet they have rarely been utilized to study the molecular evolution of peptides. Here, we highlight areas in which 3D structures can be particularly useful for studying the molecular evolution of peptide toxins. Although we focus our discussion on animal toxins, including one of the most widespread disulfide-rich peptide folds known, the inhibitor cystine knot, our conclusions should be widely applicable to studies of the evolution of disulfide-constrained peptides. We show that conserved 3D folds can be used to identify evolutionary links and test hypotheses regarding the evolutionary origin of peptides with extremely low sequence identity; construct accurate multiple sequence alignments; and better understand the evolutionary forces that drive the molecular evolution of peptides.
Also watch the video abstract
3D structures remain greatly underutilized as tools for studying the evolution of cysteine-rich peptides. Using the inhibitor cystine knot (ICK) fold as an example, we highlight areas in which 3D structures are particularly useful for uncovering structural and functional adaptations in venom peptides and elucidating their evolutionary history.