Dissertation
Biodiscovery of Venom Proteins in the Bluebottle Jellyfish, Physalia utriculus
University of the Sunshine Coast, Queensland
Doctor of Philosophy, University of the Sunshine Coast, Queensland
2025
DOI:
https://doi.org/10.25907/00948
Abstract
Jellyfish venoms are complex mixtures of bioactive compounds with immense therapeutic potential, yet they remain underexplored due to challenges in extraction, purification, and bioassay standardization. This thesis investigated the venom of Physalia utriculus (bluebottle jellyfish), initially focusing on optimising venom extraction methods, then proteomic profiling, and functional characterization of novel toxins. A comprehensive review of jellyfish venom research (1975-2022) identified the box jellyfish, Chironex fleckeri, as the most extensively studied species, with osmotic autolysis extraction and two-step liquid chromatography recognised as best practices for preserving venom bioactivity. A high-quality transcriptome of P. utriculus dactylzooids was assembled, yielding 34,471 unigenes encoding 15,860 proteins, with 259 unique venom-like proteins identified. Among these, 29 candidate toxins were characterized, of which there was six highly expressed heme-binding protein 2/SOUL (HBP2/SOUL). Venom extraction using unbuffered MQ water medium yielded the highest bioactivity (LD50 51.2 μg/mL) based on shrimp toxicity assays, while buffered extractions showed reduced toxicity. Fractionation of P. utriculus crude venom using RP-HPLC revealed three toxic regions (TR1 LD50 = 3 μg/mL, TR2 LD50 = 63 μg/mL and TR3 = 30 μg/mL ), with TR1 exhibiting the highest acute toxicity. TR1 and TR2 appeared to contain the majority of the potent small molecule toxins, with TR1 causing artemia death in under an hour. TR1 and TR2 are both recommended for future studies into small molecule toxicity. As TR3 was the only faction to contain clear evidence of proteins, it was selected for proteomic analysis. The analysis identified multiple proteins in TR3, including HBP2/SOUL proteins that were speculated to be involved in reactive oxygen species generation and cytotoxicity. A novel peptide, termed P. utriculus peptide TX01 (PupTX01), which is derived from HBP2/SOUL, was identified as a cell-penetrating peptide (CPP). In silico structural analyses revealed insights into its amphipathic nature, disulphide bonding, and potential α-helical secondary structure, supporting its membrane-translocating capabilities. Cellbased fluorescence assays confirmed that PupTX01 was cell penetrating, demonstrating intracellular uptake into human fibroblasts. This highlights its potential as a therapeutic delivery vehicle. In silico docking indicated that while PupTX01 binds heme, its toxic mechanism likely involves mitochondrial targeting and oxidative stress induction. This research advances our understanding of jellyfish venom complexity, emphasizing the need for precise venom extraction and characterization protocols. It highlighted PupTX01 as a promising candidate for therapeutic applications and underscores the potential of venom-derided peptides in drug delivery and toxin research. Future directions will focus on the elucidating the structures of unidentified small molecules in toxic fractions and the mechanistic exploration of PupTX01’s mechanistic role in cell death pathways.
Details
- Title
- Biodiscovery of Venom Proteins in the Bluebottle Jellyfish, Physalia utriculus
- Authors
- Blake Lausen - University of the Sunshine Coast, Queensland, School of Science, Technology and Engineering
- Contributors
- Tianfang Wang (Principal Supervisor) - University of the Sunshine Coast, Queensland, Centre for BioinnovationScott Cummins (Co-Supervisor) - University of the Sunshine Coast, Queensland, Centre for BioinnovationAshish Sethi (Consultant Supervisor) - Australian Nuclear Science and Technology Organisation
- Awarding institution
- University of the Sunshine Coast, Queensland
- Degree awarded
- Doctor of Philosophy
- Publisher
- University of the Sunshine Coast, Queensland
- DOI
- 10.25907/00948
- Grant note
- Australian Nuclear Science and Technology Organisation (AS233/SAXS/20392)
- Organisation Unit
- School of Science, Technology and Engineering
- Language
- English
- Record Identifier
- 991148640002621
- Output Type
- Dissertation
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