title: Insight into a natural Diels-Alder reaction from the structure of macrophomate synthase.
abstract: The Diels-Alder reaction, which forms a six-membered ring from an alkene (dienophile) and a 1,3-diene, is synthetically very useful for construction of cyclic products with high regio- and stereoselectivity under mild conditions. It has been applied to the synthesis of complex pharmaceutical and biologically active compounds. Although evidence on natural Diels-Alderases has been accumulated in the biosynthesis of secondary metabolites, there has been no report on the structural details of the natural Diels-Alderases. The function and catalytic mechanism of the natural Diels-Alderase are of great interest owing to the diversity of molecular skeletons in natural Diels-Alder adducts. Here we present the 1.70 A resolution crystal structure of the natural Diels-Alderase, fungal macrophomate synthase (MPS), in complex with pyruvate. The active site of the enzyme is large and hydrophobic, contributing amino acid residues that can hydrogen-bond to the substrate 2-pyrone. These data provide information on the catalytic mechanism of MPS, and suggest that the reaction proceeds via a large-scale structural reorganization of the product.
authors.affiliation: Division of Biological Science, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan.
authors.forename: Toyoyuki
authors.initials: T
authors.lastname: Ose
authors.forename: Kenji
authors.initials: K
authors.lastname: Watanabe
authors.forename: Takashi
authors.initials: T
authors.lastname: Mie
authors.forename: Mamoru
authors.initials: M
authors.lastname: Honma
authors.forename: Hiromi
authors.initials: H
authors.lastname: Watanabe
authors.forename: Min
authors.initials: M
authors.lastname: Yao
authors.forename: Hideaki
authors.initials: H
authors.lastname: Oikawa
authors.forename: Isao
authors.initials: I
authors.lastname: Tanaka
mesh_terms: D000438:Alcohols / Q000378:metabolism; D001665:Binding Sites; D002384:Catalysis; D018360:Crystallography, X-Ray; D003500:Cyclization; D005658:Fungi / Q000201:enzymology*; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D008274:Magnesium / Q000378:metabolism; D008958:Models, Molecular; D009097:Multienzyme Complexes / Q000737:chemistry* / Q000378:metabolism*; D011487:Protein Conformation; D011753:Pyrones / Q000378:metabolism; D019289:Pyruvic Acid / Q000378:metabolism; D055672:Static Electricity; D013329:Structure-Activity Relationship
chemical_list: D000438:Alcohols; D009097:Multienzyme Complexes; D011753:Pyrones; C408144:macrophomate synthase; D019289:Pyruvic Acid; D008274:Magnesium