The role of defensive ecological interactions in the evolution of conotoxins

Abstract

Venoms comprise of complex mixtures of peptides evolved for predation and defensive purposes. Remarkably, some carnivorous cone snails can inject two distinct venoms in response to predatory or defensive stimuli, providing a unique opportunity to study separately how different ecological pressures contribute to toxin diversification. Here, we report the extraordinary defensive strategy of the Rhizoconus subgenus of cone snails. The defensive venom from this worm-hunting subgenus is unusually simple, almost exclusively composed of αD-conotoxins instead of the ubiquitous αA-conotoxins found in the more complex defensive venom of mollusc- and fish-hunting cone snails. A similarly compartmentalized venom gland as those observed in the other dietary groups facilitates the deployment of this defensive venom. Transcriptomic analysis of a Conus vexillum venom gland revealed the αD-conotoxins as the major transcripts, with lower amounts of 15 known and four new conotoxin superfamilies also detected with likely roles in prey capture. Our phylogenetic and molecular evolution analysis of the αD-conotoxins from five subgenera of cone snails suggests they evolved episodically as part of a defensive strategy in the Rhizoconus subgenus. Thus, our results demonstrate an important role for defence in the evolution of conotoxins.

Marine natural products

“…693 Some carnivorous cone snails, including wormhunting snails of the subgenus Rhizoconus, have evolved two distinct venomsone set of peptides for defence, and another set for predation. 694 A phylogenetic and molecular evolution analysis of aD-conotoxins suggests that they evolved as part of a defensive strategy in this subgenus.…”

Screening and Validation of Highly-Efficient Insecticidal Conotoxins from a Transcriptome-Based Dataset of Chinese Tubular Cone Snail

“…Cone snails, a large group of carnivorous predators, are usually classified into fish-hunting, snail-hunting and worm-hunting groups [ 1 , 2 , 3 ]. They are effectively venomous to worms, snails, and fishes by using a deadly combination of paralyzing conotoxins.…”

A Transcriptomic Survey of Ion Channel-Based Conotoxins in the Chinese Tubular Cone Snail (Conus betulinus)

“…All cone snails constitute a single, but the largest, genus of invertebrate marine animals, which is the only genus of the Conidae family within the Conoidea superfamily which belongs to the taxonomic class Neogastropoda [ 6 , 7 ]. Conus species inhabit throughout tropical, subtropical, and temperate oceans in the Indo-West Pacific region, such as South China sea, Philippines and Australia [ 8 ]. Despite the relatively young age of the genus Conus , the slow-moving cone snails have developed successful strategies to subdue prey and defence against foes [ 5 , 9 ], including a highly complex cocktail of potent venom components with a great specificity towards a wide range of physiological targets [ 10 , 11 ].…”