Structural and functional characterisation of a novel peptide from the Australian sea anemone Actinia tenebrosa

• Published in: Toxicon (Oxford) 2019-10, Vol.168, p.104-112
• Main Authors: Elnahriry, Khaled A., Wai, Dorothy C.C., Krishnarjuna, Bankala, Badawy, Noha N., Chittoor, Balasubramanyam, MacRaild, Christopher A., Williams-Noonan, Billy J., Surm, Joachim M., Chalmers, David K., Zhang, Alan H., Peigneur, Steve, Mobli, Mehdi, Tytgat, Jan, Prentis, Peter, Norton, Raymond S.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Cell Line, Tumor; Cysteine-containing peptide; Decapoda; Humans; Lipid interactions; MCF-7 Cells; Molecular Dynamics Simulation; NMR spectroscopy; Oocytes; Peptides - chemical synthesis; Peptides - chemistry; Peptides - toxicity; Sea anemone; Sea Anemones - chemistry; Structure; Transcriptome; Xenopus laevis
• ISSN: 0041-0101; 1879-3150
• DOI: 10.1016/j.toxicon.2019.07.002

Sea anemone venoms have long been recognised as a rich source of peptides with interesting pharmacological and structural properties. Our recent transcriptomic studies of the Australian sea anemone Actinia tenebrosa have identified a novel 13-residue peptide, U-AITx-Ate1. U-AITx-Ate1 contains a single disulfide bridge and bears no significant homology to previously reported amino acid sequences of peptides from sea anemones or other species. We have produced U-AITx-Ate1 using solid-phase peptide synthesis, followed by oxidative folding and purification of the folded peptide using reversed-phase high-performance liquid chromatography. The solution structure of U-AITx-Ate1 was determined based on two-dimensional nuclear magnetic resonance spectroscopic data. Diffusion-ordered NMR spectroscopy revealed that U-AITx-Ate1 was monomeric in solution. Perturbations in the 1D 1H NMR spectrum of U-AITx-Ate1 in the presence of dodecylphosphocholine micelles together with molecular dynamics simulations indicated an interaction of U-AITx-Ate1 with lipid membranes, although no binding was detected to 100% POPC and 80% POPC: 20% POPG lipid nanodiscs by isothermal titration calorimetry. Functional assays were performed to explore the biological activity profile of U-AITx-Ate1. U-AITx-Ate1 showed no activity in voltage-clamp electrophysiology assays and no change in behaviour and mortality rates in crustacea. Moderate cytotoxic activity was observed against two breast cancer cell lines. [Display omitted] •The 13-residue peptide UAITx-Ate1 was identified in the transcriptome of the sea anemone Actinia tenebrosa.•The transcript abundance was high in tentacles but low in acrorhagi and mesenteric filaments.•The three-dimensional structure of UAITx-Ate1 consists of an extended loop structure with no helices or β-sheets.•U-AITx-Ate1 has weak affinity for biological membranes.•Moderate cytotoxic activity was observed against breast cancer cell lines.