title: 4-Hydroxy-2-pyrone formation by chalcone and stilbene synthase with nonphysiological substrates.
abstract: Valerophenone synthase (VPS) is a polyketide synthase that catalyzes the formation of the phloroglucinol derivatives in the synthesis of the bitter acids in hop (Humulus lupulus). The reaction uses isovaleryl-CoA or isobutyryl-CoA, but otherwise it is identical to that of the chalcone synthase in flavonoid biosynthesis. Our study showed that chalcone synthase can perform the function of VPS, but not perfectly, because the majority of the reactions terminated after two condensation reactions (products: 4-hydroxy-2-pyrone derivatives). The same experiments with stilbene synthase yielded exclusively the 4-hydroxy-2-pyrone derivatives, not the products expected from three condensation reactions. The results are discussed in the context of the functional diversity and evolution in the family of CHS-related polyketide synthases.
authors.affiliation: Institut für Biologie II, Universität Freiburg, Germany.
authors.forename: K W
authors.initials: KW
authors.lastname: Zuurbier
authors.forename: J
authors.initials: J
authors.lastname: Leser
authors.forename: T
authors.initials: T
authors.lastname: Berger
authors.forename: A J
authors.initials: AJ
authors.lastname: Hofte
authors.forename: G
authors.initials: G
authors.lastname: Schröder
authors.forename: R
authors.initials: R
authors.lastname: Verpoorte
authors.forename: J
authors.initials: J
authors.lastname: Schröder
mesh_terms: D000217:Acyltransferases / Q000737:chemistry / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism; D011753:Pyrones / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D010940:Plant Proteins; D011753:Pyrones; D000217:Acyltransferases; C022674:stilbene synthase; C020141:flavanone synthetase