title: Structure of macrophomate synthase.
abstract: Macrophomate synthase (MPS) is an enzyme that catalyzes an extraordinarily complex conversion reaction, including two decarboxylations, two carbon-carbon bond formations and a dehydration, to form the benzoate analogue macrophomate from a 2-pyrone derivative and oxalacetate. Of these reactions, the two carbon-carbon bond formations are especially noteworthy because previous experiments have indicated that they proceed via a Diels-Alder reaction, one of the most widely used reactions in organic synthesis. The structural evidence that MPS catalyzes an intermolecular Diels-Alder reaction has been reported recently [Ose et al. (2003), Nature (London), 422, 185-189]. Interestingly, the tertiary structure as well as the quaternary structure of MPS are similar to those of 2-dehydro-3-deoxygalactarate (DDG) aldolase, a carbon-carbon bond-forming enzyme that catalyzes the reversible reaction of aldol condensation/cleavage. Here, the structure of MPS is described in detail and compared with that of DDG aldolase. Both enzymes have a (beta/alpha)(8)-barrel fold and are classified as belonging to the enolase superfamily based on their reaction strategy. The basic principles for carbon-carbon bond formation used by both MPS and DDG aldolase are the same with regard to trapping the enolate substrate and inducing subsequent reaction. The major differences in the active sites between these two enzymes are the recognition mechanisms of the second substrates, 2-pyrone and DDG, respectively.
authors.affiliation: Division of Biological Sciences, 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: Min
authors.initials: M
authors.lastname: Yao
authors.forename: Mamoru
authors.initials: M
authors.lastname: Honma
authors.forename: Hideaki
authors.initials: H
authors.lastname: Oikawa
authors.forename: Isao
authors.initials: I
authors.lastname: Tanaka
mesh_terms: D000446:Aldehyde-Lyases / Q000737:chemistry; D000595:Amino Acid Sequence; D001203:Ascomycota / Q000201:enzymology*; D001665:Binding Sites; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009097:Multienzyme Complexes / Q000737:chemistry* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment
chemical_list: D009097:Multienzyme Complexes; C408144:macrophomate synthase; D000446:Aldehyde-Lyases; C413570:2-dehydro-3-deoxygalactarate aldolase