title: The Catalytic Mechanism of a Natural Diels-Alderase Revealed in Molecular Detail.
abstract: The Diels-Alder reaction, a [4 + 2] cycloaddition of a conjugated diene to a dienophile, is one of the most powerful reactions in synthetic chemistry. Biocatalysts capable of unlocking new and efficient Diels-Alder reactions would have major impact. Here we present a molecular-level description of the reaction mechanism of the spirotetronate cyclase AbyU, an enzyme shown here to be a bona fide natural Diels-Alderase. Using enzyme assays, X-ray crystal structures, and simulations of the reaction in the enzyme, we reveal how linear substrate chains are contorted within the AbyU active site to facilitate a transannular pericyclic reaction. This study provides compelling evidence for the existence of a natural enzyme evolved to catalyze a Diels-Alder reaction and shows how catalysis is achieved.
authors.affiliation: School of Biochemistry, Biomedical Sciences Building, University of Bristol , University Walk, Bristol BS8 1TD, United Kingdom.|BrisSynBio Synthetic Biology Research Centre, Life Sciences Building, University of Bristol , Tyndall Avenue, Bristol BS8 1TQ, United Kingdom.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Byrne
authors.affiliation: School of Chemistry, University of Bristol , Cantock's Close, Bristol BS8 1TS, United Kingdom.
authors.forename: Nicholas R
authors.initials: NR
authors.lastname: Lees
authors.affiliation: BrisSynBio Synthetic Biology Research Centre, Life Sciences Building, University of Bristol , Tyndall Avenue, Bristol BS8 1TQ, United Kingdom.|School of Chemistry, University of Bristol , Cantock's Close, Bristol BS8 1TS, United Kingdom.
authors.forename: Li-Chen
authors.initials: LC
authors.lastname: Han
authors.affiliation: School of Biochemistry, Biomedical Sciences Building, University of Bristol , University Walk, Bristol BS8 1TD, United Kingdom.|BrisSynBio Synthetic Biology Research Centre, Life Sciences Building, University of Bristol , Tyndall Avenue, Bristol BS8 1TQ, United Kingdom.|School of Chemistry, University of Bristol , Cantock's Close, Bristol BS8 1TS, United Kingdom.
authors.forename: Marc W
authors.initials: MW
authors.lastname: van der Kamp
authors.affiliation: BrisSynBio Synthetic Biology Research Centre, Life Sciences Building, University of Bristol , Tyndall Avenue, Bristol BS8 1TQ, United Kingdom.|School of Chemistry, University of Bristol , Cantock's Close, Bristol BS8 1TS, United Kingdom.
authors.forename: Adrian J
authors.initials: AJ
authors.lastname: Mulholland
authors.affiliation: School of Biology, Newcastle University , Ridley Building, Newcastle NE1 7RU, United Kingdom.|Centre for Synthetic Biology and the Bioeconomy, Newcastle University , Baddiley-Clark Building, Newcastle NE2 4AX, United Kingdom.
authors.forename: James E M
authors.initials: JE
authors.lastname: Stach
authors.affiliation: BrisSynBio Synthetic Biology Research Centre, Life Sciences Building, University of Bristol , Tyndall Avenue, Bristol BS8 1TQ, United Kingdom.|School of Chemistry, University of Bristol , Cantock's Close, Bristol BS8 1TS, United Kingdom.
authors.forename: Christine L
authors.initials: CL
authors.lastname: Willis
authors.affiliation: School of Biochemistry, Biomedical Sciences Building, University of Bristol , University Walk, Bristol BS8 1TD, United Kingdom.|BrisSynBio Synthetic Biology Research Centre, Life Sciences Building, University of Bristol , Tyndall Avenue, Bristol BS8 1TQ, United Kingdom.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Race
mesh_terms: D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry / Q000378:metabolism; D002384:Catalysis; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D061565:Cycloaddition Reaction; D053138:Cyclohexenes / Q000737:chemistry; D004798:Enzymes / Q000737:chemistry; D008958:Models, Molecular; D011789:Quantum Theory; D014961:X-Ray Diffraction
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D053138:Cyclohexenes; D004798:Enzymes; C509797:abyssomicin C