Venom composition of the ant Tetraponera rufonigra reveals insights into the evolution of dimeric ant venom peptides.

The majority of ant species are venomous, and in most lineages, peptide toxins dominate venom composition. Here we investigated the venom of the ant Tetraponera rufonigra (subfamily Pseudomyrmecinae). The major active component, Tr1a, is a homodimeric peptide that is cytolytic, activates mammalian sensory neurons and is insecticidal. Structural analyses show that Tr1a consists of two identical peptide chains arranged as antiparallel α-helices and covalently linked by three interchain disulfide bonds, forming a symmetrical amphipathic dimer. We demonstrate that dimeric venom peptides with similar biological activities have evolved independently multiple times across ants. The repeated evolution of dimeric venom peptides in ants highlights the evolutionary plasticity of ant venom and the role of convergence in shaping ant venom composition.