Diversification of a single ancestral gene into a successful toxin superfamily in highly venomous Australian funnel-web spiders

摘要: Spiders have evolved pharmacologically complex venoms that serve to rapidly subdue prey and deter predators. The major toxic factors in most spider are small, disulfide-rich peptides. While there is abundant evidence snake by recruitment of genes encoding normal body proteins followed extensive gene duplication accompanied explosive structural functional diversification, the evolutionary trajectory spider-venom peptides less clear. Here we present a spider-toxin superfamily high degree sequence diversity has via accelerated diversification single ancestral gene. within this toxin translated as prepropeptides posttranslationally processed yield mature toxin. N-terminal signal sequence, well protease recognition site at junction propeptide conserved, whereas remainder sequences variable. All transcripts exhibit striking cysteine codon bias. We show different pharmacological classes toxins peptide under selection pressures. Overall, study reinforces hypothesis spiders use combinatorial library strategy evolve cocktail target neuronal receptors ion channels ω-hexatoxins insect voltage-gated calcium influence positive Darwinian an episodic fashion, κ-hexatoxins calcium-activated potassium appear be negative selection. A majority diversifying sites concentrated on molecular surface toxins, thereby facilitating neofunctionalisation leading new pharmacology.