From Tryptophan to Toxin: Nature's Convergent Biosynthetic Strategy to Aetokthonotoxin.

Abstract

Aetokthonotoxin (AETX) is a cyanobacterial neurotoxin that causes vacuolar myelinopathy, a neurological disease that is particularly deadly to bald eagles in the United States. The recently characterized AETX is structurally unique among cyanotoxins and is composed of a pentabrominated biindole nitrile. Herein we report the discovery of an efficient, five-enzyme biosynthetic pathway that the freshwater cyanobacterium Aetokthonos hydrillicola uses to convert two molecules of tryptophan to AETX. We demonstrate that the biosynthetic pathway follows a convergent route in which two functionalized indole monomers are assembled and then reunited by biaryl coupling catalyzed by the cytochrome P450 AetB. Our results revealed enzymes with novel biochemical functions, including the single-component flavin-dependent tryptophan halogenase AetF and the iron-dependent nitrile synthase AetD.

• Authors: Sanjoy Adak, April L Lukowski, Rebecca J B Schäfer, Bradley S Moore
• Journal: Journal of the American Chemical Society (J Am Chem Soc) Vol. 144 Issue 7 Pg. 2861-2866 (02 23 2022) ISSN: 1520-5126 [Electronic] United States
• PMID: 35142504 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• Cytochrome P-450 Enzyme System
• Indoles
• Neurotoxins
• Nitriles
• Oxidoreductases
• Tryptophan
• tryptophan halogenase
• Tryptophanase
• aetokthonotoxin

Topics

• Cyanobacteria (genetics, metabolism)
• Cytochrome P-450 Enzyme System (metabolism)
• Indoles (metabolism)
• Multigene Family
• Neurotoxins (biosynthesis)
• Nitriles (metabolism)
• Oxidoreductases (metabolism)
• Tryptophan (metabolism)
• Tryptophanase (metabolism)