Unveiling the molecular diversity of toxins and non-toxins in the medicinal sea snake Hydrophis cyanocinctus through integrated venomics investigation.

Sea snake venom systems provide exceptional models for studying marine adaptation and are rich sources of bioactive molecules for drug discovery. To comprehensively characterize the venom diversity of the medicinal sea snake Hydrophis cyanocinctus, this study employed an integrated multi-omics strategy. We performed deep proteomic profiling of its venom and venom gland using both data-independent acquisition (DIA) and tandem mass tag (TMT) techniques, underpinned by a previously established chromosome-level genome and PacBio full-length transcriptomics. Our analysis revealed a distinctive proteome where four three-finger toxins (3FTxs) dominate the toxic arsenal (65%), with long-chain neurotoxins (LNTXs) showing signs of rapid evolution, diverse alternative splicing proteoforms, and marine prey-specific structural adaptation. Crucially, we systematically cataloged a vast repertoire of non-toxin proteins, which constitute the majority (71%) of the venom mass. Functional and protein-protein interaction (PPI) network analyses indicated that these non-toxin components, including abundant immunoglobulin (Ig)-like proteins and key regulators like calglandulin (CAL), are integral to a coordinated cellular system supporting high-volume toxin biosynthesis, secretion, and potential immune defense. This work provides a holistic molecular atlas of a sea snake venom system, bridging genetic diversity with proteomic expression phenotype, and offers a valuable resource for understanding venom evolution and for mining novel marine-derived pharmacologically active components.