An Esterase‐like Lyase Catalyzes Acetate Elimination in Spirotetronate/Spirotetramate Biosynthesis. Issue 8 (21st January 2019)

• Record Type: Journal Article
• Authors: Lees, Nicholas R.; Han, Li‐Chen; Byrne, Matthew J.; Davies, Jonathan A.; Parnell, Alice E.; Moreland, Pollyanna E. J.; Stach, James E. M.; van der Kamp, Marc W.; Willis, Christine L.; Race, Paul R.
• Is Part Of: Angewandte Chemie international edition. Volume 58:Issue 8(2019)
• Page Start: 2305
• Page End: 2309
• Publication Date: 2019-01-21
• Subjects: antibiotics -- biocatalysis -- enzyme structure -- enzymology -- polyketides; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201812105
• Languages: English
• ISSNs: 1433-7851

Abstract

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. Abstract : To eliminate, or to hydrolyze, that is the question : Structural, mechanistic, and computational studies of the abyssomicin C pathway enzyme AbyA5 establish the molecular origins of enzyme‐catalyzed acetate elimination. The unexpected acetyl‐esterase‐like scaffold of the protein is shown to support both acetate elimination and ester hydrolysis, in a manner dictated by substrate identity.