Selective toxin–lipid membrane interactions of natural, haemolytic Scyphozoan toxins analyzed by surface plasmon resonance

Molecular dissection of box jellyfish venom cytotoxicity highlights an effective venom antidote

The box jellyfish Chironex fleckeri is extremely venomous, and envenoming causes tissue necrosis, extreme pain and death within minutes after severe exposure. Despite rapid and potent venom action, basic mechanistic insight is lacking. Here we perform molecular dissection of a jellyfish venom-induced cell death pathway by screening for host components required for venom exposure-induced cell death using genome-scale lenti-CRISPR mutagenesis. We identify the peripheral membrane protein ATP2B1, a calcium transporting ATPase, as one host factor required for venom cytotoxicity. Targeting ATP2B1 prevents venom action and confers long lasting protection. Informatics analysis of host genes required for venom cytotoxicity reveal pathways not previously implicated in cell death. We also discover a venom antidote that functions up to 15 minutes after exposure and suppresses tissue necrosis and pain in mice. These results highlight the power of whole genome CRISPR screening to investigate venom mechanisms of action and to rapidly identify new medicines.

Box jellyfish venom causes tissue damage, pain, and death through unknown molecular mechanisms. Here, Lau et al. perform a CRISPR screen to identify genes required for venom action and use this information to develop an antidote that blocks venom-induced pain and tissue damage in vivo.

Preliminary results of the in vivo and in vitro characterization of a tentacle venom fraction from the jellyfish Aurelia aurita

The neurotoxic effects produced by a tentacle venom extract and a fraction were analyzed and correlated by in vivo and in vitro approaches. The tentacle venom extract exhibited a wide range of protein components (from 24 to >225 kDa) and produced tetanic reactions, flaccid paralysis, and death when injected into crabs. Two chromatography fractions also produced uncontrolled appendix movements and leg stretching. Further electrophysiological characterization demonstrated that one of these fractions potently inhibited ACh-elicited currents mediated by both vertebrate fetal and adult muscle nicotinic acetylcholine receptors (nAChR) subtypes. Receptor inhibition was concentration-dependent and completely reversible. The calculated IC(50) values were 1.77 μg/μL for fetal and 2.28 μg/μL for adult muscle nAChRs. The bioactive fraction was composed of a major protein component at ~90 kDa and lacked phospholipase A activity. This work represents the first insight into the interaction of jellyfish venom components and muscle nicotinic receptors.

A novel proteinaceous cytotoxin from the northern Scyphozoa Cyanea capillata (L.) with structural homology to cubozoan haemolysins

It is well known that jellyfish are producers of complex mixtures of proteinaceous toxins for prey capture and defence. Nevertheless, studies on boreal scyphozoans concerning venom composition and toxic effects are rare. Here the isolation of a novel cytotoxic protein from the fishing tentacle venom of Cyanea capillata (L. 1758) using bioactivity-guided, multidimensional liquid chromatography is described. The crude venom was purified utilising preparative size-exclusion, ion-exchange, and reversed-phase chromatography. The cytotoxicity of resulting chromatographic fractions has been proven by a dye-uptake assay with the human hepatocyte cell line HepG2. The final purification step yielded, among other fractions, a fraction containing a single protein (named CcTX-1) with a molecular weight of its main isoform of 31.17 kDa The purification process leads to an increased cytotoxic activity per protein equivalents and the finally isolated CcTX-1 caused a nearly total loss of cell viability at a protein concentration of 1.3 μg mL⁻¹ corresponding to 0.4 μg/10⁵ cells. De novo sequencing of CcTX-1 was conducted after enzymatic digestion and subsequent matrix-assisted laser desorption ionisation time-of-flight/time-of-flight mass spectrometry (MALDI-ToF/ToF MS/MS). The obtained sequence data provide an approximate 85% description of the amino acid sequence. This sequence information partially matched that of two known haemolytic proteins of two cubozoan species: CaTX-1 from Carybdea alata Reynaud, 1830 and CrTX-1 from Carybdea rastonii Haacke, 1886.