Antibiotic origami: selective formation of spirotetronates in abyssomicin biosynthesis

• Published in: Chemical science (Cambridge) Vol. 15; no. 34; pp. 14009 - 14015
• Main Authors: Mbatha, Sbusisiwe Z, Back, Catherine R, Devine, Andrew J, Mulliner, Hannah M, Johns, Samuel T, Lewin, Harry, Cheung, Kaiman A, Zorn, Katja, Stach, James E M, Hayes, Martin A, van der Kamp, Marc W, Race, Paul R, Willis, Christine L
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 12.08.2024; The Royal Society of Chemistry
• Subjects: Biosynthesis; Chemistry; Cycloaddition; Diels-Alder reactions; Dynamic structural analysis; Enantiomers; Molecular dynamics; Natural products; Stereoselectivity; Substrates
• DOI: 10.1039/d4sc03253e
• ISSN: 2041-6520

The abyssomicins are a structurally intriguing family of bioactive natural products that include compounds with potent antibacterial, antitumour and antiviral activities. The biosynthesis of the characteristic abyssomicin spirotetronate core occurs an enzyme-catalysed intramolecular Diels-Alder reaction, which proceeds one of two distinct stereochemical pathways to generate products differing in configuration at the C15 spirocentre. Using the purified spirotetronate cyclases AbyU (from abyssomicin C/atrop-abyssomicin C biosynthesis) and AbmU (from abyssomicin 2/neoabyssomicin biosynthesis), in combination with synthetic substrate analogues, here we show that stereoselectivity in the spirotetronate-forming [4 + 2]-cycloaddition is controlled by a combination of factors attributable to both the enzyme and substrate. Furthermore, an achiral substrate was enzymatically cyclised to a single enantiomer of a spirocyclic product. X-ray crystal structures, molecular dynamics simulations, and assessment of substrate binding affinity and reactivity in both AbyU and AbmU establish the molecular determinants of stereochemical control in this important class of biocatalysts.