Lyngbyatoxin-a

Lyngbyatoxin-a is a type of alkaloid cyanotoxin produced by certain cyanobacteria species, most notably Moorea producens. It is produced as defense mechanism to ward off any would-be predators of the bacterium, being a potent blister agent as well as carcinogen. Low concentrations cause a common skin condition known as seaweed dermatitis.

Biosynthesis

Lyngbyatoxin is a terpenoid indole alkaloid hybrid that belongs to the class of non-ribosomal peptides. Lyngbyatoxin contains a nucleophilic indole ring that takes part in the activation of protein kinases. Figure 1, shows the biosynthesis of Lyngbyatoxin reported by Neilan et al. and Gerwick et al. The non-ribosomal peptide synthase LtxA protein condenses L-methyl-valine and L-tryptophan to form the linear dipeptide N-methyl-L-valyl-L-tryptophan. The latter is released via a NADPH-dependent reductive cleavage to form the aldehyde which is subsequently reduced to the corresponding alcohol. A P450-dependent monooxygenase called LtxB then performs the oxidation and subsequent cyclization of N-methyl-L-valyl-L-tryptophan. Finally, LtxC transfers a geranyl functional group from geranyl pyrophosphate to carbon number 7 of the indole ring.