Convergent recruitment of adamalysin-like metalloproteases in the venom of the red bark centipede (Scolopocryptops sexspinosus)

Abstract

Many venom proteins have presumably been convergently recruited by taxa from diverse venomous lineages. These toxic proteins have characteristics that allow them to remain stable in solution and have a high propensity for toxic effects on prey and/or potential predators. Despite this well-established convergent toxin recruitment, some toxins seem to be lineage specific. To further investigate the toxic proteins found throughout venomous lineages, venom proteomics and venom-gland transcriptomics were performed on two individual red bark centipedes (Scolopocryptops sexspinosus). Combining the protein phenotype with the transcript genotype resulted in the first in-depth venom characterization of S. sexspinosus, including 72 venom components that were identified in both the transcriptome and proteome and 1468 nontoxin transcripts identified in the transcriptome. Ten different toxin families were represented in the venom and venom gland with the majority of the toxins belonging to metalloproteases, CAPS (cysteine-rich secretory protein, antigen 5, and pathogenesis-related 1 proteins), and β-pore-forming toxins. Nine of these toxin families shared a similar proteomic structure to venom proteins previously identified from other centipedes. However, the most highly expressed toxin family, the adamalysin-like metalloproteases, has until now only been observed in the venom of snakes. We confirmed adamalysin-like metalloprotease activity by means of in vivo functional assays. The recruitment of an adamalysin-like metalloprotease into centipede venom represents a striking case of convergent evolution.