PHAB toxins: a unique family of predatory sea anemone toxins evolving via intra-gene concerted evolution defines a new peptide fold
Madio, B.; Peigneur, S.; Chin, Y.K.Y.; Hamilton, B.; Henriques, S.T.; Smith, J.J.; Cristofori-Armstrong, B.; Dekan, Z.; Boughton, B.A.; Alewood, P.F.; Tytgat, J.; King, G.F.; Undheim, E.A.B. (2018). PHAB toxins: a unique family of predatory sea anemone toxins evolving via intra-gene concerted evolution defines a new peptide fold. Cellular and molecular life sciences 75(24): 4511-4524. https://dx.doi.org/10.1007/s00018-018-2897-6 In: Cellular and molecular life sciences. ISSN 1420-682X; e-ISSN 1420-9071, more |  |
| Keyword | | | Author keywords | Neurotoxin; Ion channel; Mass spectrometry imaging; 3D structure;Concerted evolution; Extreme resolution mass spectrometry imaging;On-tissue reduction alkylation |
| Authors | | Top | - Madio, B.
- Peigneur, S., more
- Chin, Y.K.Y.
- Hamilton, B.
- Henriques, S.T.
| - Smith, J.J.
- Cristofori-Armstrong, B.
- Dekan, Z.
- Boughton, B.A.
| - Alewood, P.F.
- Tytgat, J., more
- King, G.F.
- Undheim, E.A.B.
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| Abstract | Sea anemone venoms have long been recognized as a rich source of peptides with interesting pharmacological and structural properties, but they still contain many uncharacterized bioactive compounds. Here we report the discovery, three-dimensional structure, activity, tissue localization, and putative function of a novel sea anemone peptide toxin that constitutes a new, sixth type of voltage-gated potassium channel (KV) toxin from sea anemones. Comprised of just 17 residues, κ-actitoxin-Ate1a (Ate1a) is the shortest sea anemone toxin reported to date, and it adopts a novel three-dimensional structure that we have named the Proline-Hinged Asymmetric β-hairpin (PHAB) fold. Mass spectrometry imaging and bioassays suggest that Ate1a serves a primarily predatory function by immobilising prey, and we show this is achieved through inhibition of Shaker-type KV channels. Ate1a is encoded as a multi-domain precursor protein that yields multiple identical mature peptides, which likely evolved by multiple domain duplication events in an actinioidean ancestor. Despite this ancient evolutionary history, the PHAB-encoding gene family exhibits remarkable sequence conservation in the mature peptide domains. We demonstrate that this conservation is likely due to intra-gene concerted evolution, which has to our knowledge not previously been reported for toxin genes. We propose that the concerted evolution of toxin domains provides a hitherto unrecognised way to circumvent the effects of the costly evolutionary arms race considered to drive toxin gene evolution by ensuring efficient secretion of ecologically important predatory toxins. |
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