A comparative analysis of toxin gene families across diverse sea anemone species

TL;DR

This study compares toxin genes in venomous sea anemones, revealing patterns of toxin distribution and diversity across species.

Contribution

The study provides the first comprehensive toxin gene analysis of the medically significant sea anemone Actinodendron plumosum and related species.

Findings

Six neurotoxin families showed taxonomic restriction across 26 sea anemone species.

Phospholipase A2 toxin family was found to be ubiquitously distributed.

Two alternative structural forms of phospholipase A2 toxin were identified.

Abstract

All species from order Actiniaria (sea anemones) are venomous, even though most are of no threat to humans. Currently, we know very little about the toxin gene complement of highly venomous members of this order. To address this gap in knowledge, we sequenced the transcriptome of the highly venomous and medically significant Hell's Fire sea anemone, Actinodendron plumosum, as well as five distantly related species, Cryptodendrum adhaesivum, Epiactis australiensis, Heteractis aurora, Isactinia olivacea and Stichodactyla mertensii. We used bioinformatic approaches to identify their toxin gene complements and performed a comparative evolutionary analysis of seven understudied toxin families. Of the 16 toxin families identified, 12–40 candidate toxins were found in the six new sea anemone transcriptomes, with only 12 candidates in eight toxin families identified in A. plumosum. Across 26 sea anemone species, six neurotoxin families showed evidence of taxonomic restriction, whereas the phospholipase A2 toxin family was ubiquitously distributed. Additionally, we identified two alternative forms for the phospholipase A2 toxin family, a 10- and 14-cysteine framework, which warrant further structural and functional characterisation. Overall, we have identified a comprehensive list of toxins from a wide diversity of sea anemone species that provides the basis for future research to structurally and functionally characterise novel candidates for potential use as therapeutics or for agricultural applications.

Image 1

•Six transcriptomes from five Actinioidea families, including the medically significant sea anemone, Actinodendron plumosum.•Comparative analysis of seven toxin families from 26 closely and distantly related species.•Six neurotoxin genes have a taxonomically restricted distribution while phospholipase A2 is ubiquitously distributed.

Six transcriptomes from five Actinioidea families, including the medically significant sea anemone, Actinodendron plumosum.

Comparative analysis of seven toxin families from 26 closely and distantly related species.

Six neurotoxin genes have a taxonomically restricted distribution while phospholipase A2 is ubiquitously distributed.

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