Abstract
We present the solution-state NMR structures and preliminary functional characterizations of three venom peptides identified from the spitting spider Scytodes thoracica. Despite little sequence identity to other venom peptides, structural characterization reveals that these peptides contain an inhibitor cystine knot motif common to many venom peptides. These are the first structures for any peptide or protein from spiders of the Scytodidae family. Many venom peptides target neuronal ion channels or receptors. However, we have not been able to determine the target of these Scytodes peptides so we can only state with certainty the channels and receptors that they do not target.
Highlights
Data Availability Statement: Sequences are available from UniProt
Disulfide-rich peptides are the dominant components in most spider venoms and they are often the key contributors to the activity and potency of the venom [8]. While these disulfiderich peptides can adopt a number of different structural motifs, the motif known as the inhibitor cystine knot (ICK) is the most widely observed
Consistent with the propeptide cleavage site we predicted based on the processing quadruplet motif (PQM) motif, previous work [15] using mass spectrometry confirmed that U5-Sth1a is present in crude Scytodes thoracica venom
Summary
Data Availability Statement: Sequences are available from UniProt (accession numbers A0A0A0V662, A0A0A0V712, and A0A0A0V633 for U3-Sth1a, U3-Sth1h, and U5-Sth1a, respectively). Disulfide-rich peptides are the dominant components in most spider venoms and they are often the key contributors to the activity and potency of the venom [8] While these disulfiderich peptides can adopt a number of different structural motifs, the motif known as the inhibitor cystine knot (ICK) is the most widely observed. Gene duplication and diversification of the peptide sequence surrounding the knotted core has allowed this ICK structure to act as an adaptable framework for a wide range of peptide sequences [12] that can target neuronal ion channels with relative selectivity and potent paralytic or lethal function [13]. Despite performing injections and topical applications of recombinantly-produced peptides into insects, fluorescent assays with ion channels, and radioligand screening against central nervous system receptors, we have not yet been able to determine the targets of these peptides
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