D-Peptidase Activity in a Marine Mollusk Detoxifies a Nonribosomal Cyclic Lipopeptide: An Ecological Model to Study Antibiotic Resistance

In the marine environment, sessile cyanobacteria have developed chemical strategies for protection against grazers. In turn, herbivores have to circumvent these defenses and in certain cases even take advantage of them as shelter from their own predators. This is the case of Stylocheilus striatus, a sea hare that feeds on Anabaena torulosa, a cyanobacterium that produces toxic cyclic lipopeptides of the laxaphycin B family. S. striatus consumes the cyanobacterium without being affected by the toxicity of its compounds and also uses it as an invisibility cloak against predators. In this article, using different substrates analogous to laxaphycin B, we demonstrate the presence of an enzyme in the digestive gland of the mollusk that is able to biotransform laxaphycin B derivatives. The enzyme belongs to the poorly known family of D-peptidases that are suspected to be involved in antibiotic resistance.

Automated summary

In the marine environment, sessile cyanobacteria have developed chemical strategies to protect themselves from grazers, while herbivores have evolved to bypass these defenses and sometimes even benefit from them. The sea hare Stylocheilus striatus feeds on a toxic cyanobacterium as a food source and uses it as a camouflage against predators, demonstrating a unique symbiotic relationship. Through research, an enzyme in the mollusk's digestive gland has been found capable of transforming toxic cyanobacterial compounds, shedding light on potential antibiotic resistance mechanisms in marine organisms.