Data from: Medically important differences in snake venom composition are dictated by distinct postgenomic mechanisms

Variation in venom composition is a ubiquitous phenomenon in snakes and
occurs both interspecifically and intraspecifically. Venom variation can
have severe outcomes for snakebite victims by rendering the specific
antibodies found in antivenoms ineffective against heterologous toxins
found in different venoms. The rapid evolutionary expansion of different
toxin-encoding gene families in different snake lineages is widely
perceived as the main cause of venom variation. However, this view is
simplistic and disregards the understudied influence that processes acting
on gene transcription and translation may have on the production of the
venom proteome. Here, we assess the venom composition of six related
viperid snakes and compare interspecific changes in the number of toxin
genes, their transcription in the venom gland, and their translation into
proteins secreted in venom. Our results reveal that multiple levels of
regulation are responsible for generating variation in venom composition
between related snake species. We demonstrate that differential levels of
toxin transcription, translation, and their posttranslational modification
have a substantial impact upon the resulting venom protein mixture.
Notably, these processes act to varying extents on different toxin
paralogs found in different snakes and are therefore likely to be as
important as ancestral gene duplication events for generating
compositionally distinct venom proteomes. Our results suggest that these
processes may also contribute to altering the toxicity of snake venoms,
and we demonstrate how this variability can undermine the treatment of a
neglected tropical disease, snakebite.