title: Biosynthetic precursors of fungal pyrrolizidines, the loline alkaloids.
abstract: Loline alkaloids are saturated pyrrolizidines with a substituted 1-amino group and an oxygen bridge between C2 and C7, and are insecticidal metabolites of plant-symbiotic fungi (endophytes). Cultures of the endophyte, Neotyphodium uncinatum, incorporated labeled L-proline and L-homoserine into the 1-aminopyrrolizidine, N-formylloline. The A-ring carbons C1-C3 and the N1 were derived from L-homoserine; the B-ring carbons C5-C8 and the ring nitrogen were derived from L-proline. Incorporation of both deuterium atoms from L-[4,4-(2H2)]homoserine and feeding tests with labeled L-methionine indicated that L-homoserine incorporation was not achieved via aspartyl semialdehyde or S-adenosylmethionine, but probably involved a highly novel N--C bond-forming gamma-substitution reaction.
authors.affiliation: Department of Plant Pathology, University of Kentucky, 1405 Veterans Drive, Lexington, KY 40546-0312, USA.
authors.forename: Jimmy D
authors.initials: JD
authors.lastname: Blankenship
authors.forename: Justin B
authors.initials: JB
authors.lastname: Houseknecht
authors.forename: Sitaram
authors.initials: S
authors.lastname: Pal
authors.forename: Lowell P
authors.initials: LP
authors.lastname: Bush
authors.forename: Robert B
authors.initials: RB
authors.lastname: Grossman
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Schardl
mesh_terms: D000470:Alkaloids / Q000096:biosynthesis*; D002967:Claviceps / Q000737:chemistry*; D003470:Culture Media; D006571:Heterocyclic Compounds / Q000737:chemistry; D006714:Homoserine / Q000737:chemistry / Q000378:metabolism; D007553:Isotope Labeling; D009682:Magnetic Resonance Spectroscopy; D009584:Nitrogen / Q000737:chemistry; D011392:Proline / Q000737:chemistry / Q000378:metabolism; D011763:Pyrrolizidine Alkaloids / Q000737:chemistry / Q000378:metabolism*
chemical_list: C494067:1-aminopyrrolizidine; D000470:Alkaloids; D003470:Culture Media; D006571:Heterocyclic Compounds; D011763:Pyrrolizidine Alkaloids; D006714:Homoserine; D011392:Proline; C059478:loline; D009584:Nitrogen