An Esterase-like Lyase Catalyzes Acetate Elimination in Spirotetronate/Spirotetramate Biosynthesis

Nicholas R Lees, Li-Chen Han, Matt Byrne, Jonathan Davies, Alice Parnell, Pollyanna Moreland, James E M Stach, Marc Van der Kamp, Chris Willis, Paul Race

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Abstract

Spirotetronate and spirotetramate natural products include a multitude of compounds with potent antimicrobial and antitumor activities. Their biosynthesis incorporates many unusual biocatalytic steps, including regio- and stereo-specific modifications, cyclizations promoted by Diels–Alderases, and acetylation-elimination reactions. Here we focus on the acetate elimination catalyzed by AbyA5, implicated in the formation of the key Diels–Alder substrate to give the spirocyclic system of the antibiotic abyssomicin C. Using synthetic substrate analogues, it is shown that AbyA5 catalyzes stereospecific acetate elimination, establishing the (R)-tetronate acetate as a biosynthetic intermediate. The X-ray crystal structure of AbyA5, the first of an acetate-eliminating enzyme, reveals a deviant acetyl esterase fold. Molecular dynamics simulations and enzyme assays show the use of a His-Ser dyad to catalyze either elimination or hydrolysis, via disparate mechanisms, under substrate control.

Original languageEnglish
Pages (from-to)2305-2309
Number of pages5
JournalAngewandte Chemie - International Edition
Volume58
Issue number8
Early online date21 Jan 2019
DOIs
Publication statusPublished - 18 Feb 2019

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Structured keywords

  • BrisSynBio
  • Bristol BioDesign Institute
  • BCS and TECS CDTs

Keywords

  • antibiotics
  • biocatalysis
  • enzyme structure
  • enzymology
  • polyketides
  • Synthetic biology

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