Journal
TOXICON
Volume 150, Issue -, Pages 50-59Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.toxicon.2018.05.006
Keywords
OspTx2b; Cysteine-rich peptide; Sea anemone; Structure; NMR spectroscopy; Potassium channel
Categories
Funding
- Australian National Health and Medical Research Council
- Australian Research Council [LP150100621]
- Australian Government Research Training Program Scholarship
- Monash University-Museum Victoria Scholarship top-up
- Wellcome Trust (UK)
- University of Queensland (Australia)
- [CELSA/17/047 - BOF/ISP]
- Australian Research Council [LP150100621] Funding Source: Australian Research Council
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Sea anemone venom is rich in bioactive compounds, including peptides containing multiple disulfide bridges. In a transcriptomic study on Oulactis sp., we identified the putative 36-residue peptide, OspTx2b, which is an isoform of the K-v channel blocker OspTx2a (Sunanda Petal. [2018] Identification, chemical synthesis, structure and function of a new K(v)1 channel blocking peptide from Oulactis sp. Peptide Science, in press). As OspTx2b contains a ShK/BgK-like cysteine framework, with high amino acid sequence similarity to BgK, we were interested to investigate its structure and function. The solution structure of OspTx2b was determined using nuclear magnetic resonance spectroscopy. OspTx2b does indeed possess a BgK-like scaffold, with the same disulfide bond connectivities. The orientation of the Lys-Tyr dyad in OspTx2b is more similar to that in ShK than in BgK. However, it failed to show against a range of voltage-gated potassium channels in Xenopus oocytes and human T lymphocytes. OspTx2b also showed no growth inhibitory activity against several strains of bacteria and fungi. Having a BgK-like fold with the Lys-Tyr dyad but no BgK-like activity highlights the importance of key amino acid residues in BgK that are missing in OspTx2b. The lack of activity against the Kv channels assessed in this study emphasises that the ShK/BgK scaffold is capable of supporting functional activity beyond potassium channel blockade.
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