title: Isotopologue profiling of triterpene formation under physiological conditions. Biosynthesis of lupeol-3-(3'-R-hydroxy)-stearate in Pentalinon andrieuxii.
abstract: The biosynthesis of lupeol-3-(3'R-hydroxy)-stearate (procrim b, 1) was investigated in the Mexican medicinal plant Pentalinon andrieuxii by (13)CO2 pulse-chase experiments. NMR analyses revealed positional enrichments of (13)C2-isotopologues in both the triterpenoid and the hydroxystearate moieties of 1. Five of the six isoprene units reflected a pattern with [1,2-(13)C2]- and [3,5-(13)C2]-isotopologues from the respective C5-precursors, IPP and DMAPP, whereas one isoprene unit in the ring E of 1 showed only the [3,5-(13)C2]-connectivity of the original C5-precursor, due to rearrangement of the dammarenyl cation intermediate during the cyclization process. The presence of (13)C2-isotopologues was indicative of [(13)C2]acetyl-CoA being the precursor units in the formation of the fatty acid moiety and of the triterpene via the mevalonate route. The observed labeling pattern was in agreement with a chair-chair-chair-boat conformation of the (S)-2,3-oxidosqualene precursor during the cyclization process, suggesting that the lupeol synthase from P. andrieuxii is of the same type as that from Olea europea and Taraxacum officinale, but different from that of Arabidopsis thaliana. The study shows that (13)CO2 pulse-chase experiments are powerful in elucidating, under in vivo conditions and in a single experiment, the biosynthesis of complex plant products including higher terpenes.
authors.affiliation: Lehrstuhl für Biochemie, Technische Universität München , Lichtenbergstr. 4, D-85747 Garching, Germany.
authors.forename: Luis M
authors.initials: LM
authors.lastname: Peña-Rodríguez
authors.forename: Alejandro
authors.initials: A
authors.lastname: Yam-Puc
authors.forename: Nihat
authors.initials: N
authors.lastname: Knispel
authors.forename: Nicholas
authors.initials: N
authors.lastname: Schramek
authors.forename: Claudia
authors.initials: C
authors.lastname: Huber
authors.forename: Christoph
authors.initials: C
authors.lastname: Graßberger
authors.forename: Fabiola G
authors.initials: FG
authors.lastname: Ramírez-Torres
authors.forename: Fabiola
authors.initials: F
authors.lastname: Escalante-Erosa
authors.forename: Karlina
authors.initials: K
authors.lastname: García-Sosa
authors.forename: Mickel R
authors.initials: MR
authors.lastname: Hiebert-Giesbrecht
authors.forename: Manuel J
authors.initials: MJ
authors.lastname: Chan-Bacab
authors.forename: Gregorio
authors.initials: G
authors.lastname: Godoy-Hernández
authors.forename: Adelbert
authors.initials: A
authors.lastname: Bacher
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Eisenreich
mesh_terms: D000595:Amino Acid Sequence; D002247:Carbon Isotopes / Q000737:chemistry*; D003500:Cyclization; D019751:Intramolecular Transferases / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D031658:Olea / Q000737:chemistry*; D053978:Pentacyclic Triterpenes / Q000096:biosynthesis* / Q000138:chemical synthesis* / Q000737:chemistry*; D013185:Squalene / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry*; D013228:Stearates / Q000138:chemical synthesis* / Q000737:chemistry; D031205:Taraxacum / Q000737:chemistry*; D014315:Triterpenes / Q000138:chemical synthesis* / Q000737:chemistry; D000094042:Lupanes
chemical_list: D002247:Carbon Isotopes; D019751:Intramolecular Transferases; D053978:Pentacyclic Triterpenes; D013185:Squalene; D013228:Stearates; D014315:Triterpenes; C002821:2,3-oxidosqualene; C000594395:lupeol-3-(3'-R-hydroxy)-stearate; D000094042:Lupanes; C117114:lupeol synthase; C010480:lupeol