title: Biosynthesis of isochorismate in Klebsiella pneumoniae: origin of O-2.
abstract: The shikimate metabolites are key precursors to a large number of natural products, including aromatic amino acids. Chorismic acid is an important branch point in the biosynthetic pathway to aromatic amino acids. Chorismic acid is also unique among natural products since it is the only compound known to undergo an enzymatic Claisen rearrangement. A metabolite of chorismic acid, isochorismic acid, first observed in Aerobacter aerogenes differs in its chemical structure by the location of the hydroxyl group and the double bonds. Isochorismic acid is a precursor to a growing number of shikimate-derived metabolites. Isochorismic acid has also been postulated to be an intermediate of m-carboxyaromatic amino acids, implying another enzymatic Claisen rearrangement. In this publication, we have isolated isochorismate synthase and found that on lyophilization the enzyme is stable for at least 6 months at -20 degrees C. Incubation of chorismate with this preparation in water enriched with 18O led to incorporation of one atom of 18O as proven from the fast atom bombardment mass spectra of the HPLC purified derived isochorismate.
authors.affiliation: Université du Québec, Institut Armand-Frappier, Laval-des-Rapides, Canada.
authors.forename: L O
authors.initials: LO
authors.lastname: Zamir
authors.forename: K A
authors.initials: KA
authors.lastname: Devor
authors.forename: R A
authors.initials: RA
authors.lastname: Jensen
authors.forename: R
authors.initials: R
authors.lastname: Tiberio
authors.forename: F
authors.initials: F
authors.lastname: Sauriol
authors.forename: O
authors.initials: O
authors.lastname: Mamer
mesh_terms: D002827:Chorismic Acid / Q000737:chemistry* / Q000378:metabolism; D053138:Cyclohexenes; D019751:Intramolecular Transferases; D007535:Isomerases / Q000378:metabolism; D007536:Isomerism; D007711:Klebsiella pneumoniae / Q000201:enzymology / Q000378:metabolism*; D013058:Mass Spectrometry
chemical_list: D053138:Cyclohexenes; C052985:isochorismic acid; D007535:Isomerases; D019751:Intramolecular Transferases; C058486:isochorismate synthase; D002827:Chorismic Acid