A genome-guided atlas to the composition, activity, and β-bungarotoxin dimerization in many-banded krait venom inferred by functional venomics

Abstract

Snakebite is a neglected tropical disease claiming ∼140,000 lives every year. One of the most medically relevant snakes of Asia is the many-banded krait (Bungarus multicinctus). Approximately 8% of the global human population is at risk of being envenomated by this species, able to cause fatal neurotoxicity. Here, we present a proteogenomic and functional assessment of theB. multicinctusvenom via genome-guided bottom-up and top-down proteomics, combined with protein profiling and bioactivity assays. We report its venom profile alongside the primary structures of its toxins, revealing a relatively simple venom containing 55 components from 16 protein families. It is largely composed by three-finger toxins and phospholipase A₂, besides acetylcholinesterase and snake venom metalloprotease. Top-down data unveiled the diversity of the highly lethal β-bungarotoxins and allowed us to infer the complex dimerization patterning of these multi-domain neurotoxins. Our functional analysis revealed thatB. multicinctusvenom exerts potent phospholipase A₂and acetylcholinesterase activities, while protease activity and effects on cell viability and release of second messengers were virtually absent. This suggests, thatB. multicinctusvenom causes its devastating neurotoxic symptoms due to a heavy reliance on phospholipase A₂and acetylcholinesterase, but without directly impairing neuron viability or via interference of second messenger release. Antibacterial and antiviral screens further revealed activity against some pathogenic microbes that warrant further translational investigations. A comparison to previously published venom proteomes ofB. multicinctusand its congeners suggests, that intraspecific venom variation occurs more widely in kraits than previously acknowledged and deserves higher attention. Overall, our investigation provides pivotal new insights into the biochemistry and pathophysiology of one of Earth’s most lethal snakes and represents an important resource to inform future proteogenomic and functional studies in krait venom and beyond.