title: Cloning and characterization of the Dictyostelium discoideum cycloartenol synthase cDNA.
abstract: Cycloartenol synthase converts oxidosqualene to cycloartenol, the first carbocyclic intermediate en route to sterols in plants and many protists. Presented here is the first cycloartenol synthase gene identified from a protist, the cellular slime mold Dictyostelium discoideum. The cDNA encodes an 81-kDa predicted protein 50-52% identical to known higher plant cycloartenol synthases and 40-49% identical to known lanosterol synthases from fungi and mammals. The encoded protein expressed in transgenic Saccharomyces cerevisiae converted synthetic oxidosqualene to cycloartenol in vitro. This product was characterized by 1H and 13C nuclear magnetic resonance and gas chromatography-mass spectrometry. The predicted protein sequence diverges sufficiently from the known cycloartenol synthase sequences to dramatically reduce the number of residues that are candidates for the catalytic difference between cycloartenol and lanosterol formation.
authors.affiliation: Department of Biochemistry and Cell Biology, Rice University, Houston, Texas, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Godzina
authors.forename: M A
authors.initials: MA
authors.lastname: Lovato
authors.forename: M M
authors.initials: MM
authors.lastname: Meyer
authors.forename: K A
authors.initials: KA
authors.lastname: Foster
authors.forename: W K
authors.initials: WK
authors.lastname: Wilson
authors.forename: W
authors.initials: W
authors.lastname: Gu
authors.forename: E L
authors.initials: EL
authors.lastname: de Hostos
authors.forename: S P
authors.initials: SP
authors.lastname: Matsuda
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004023:Dictyostelium / Q000201:enzymology* / Q000235:genetics; D006801:Humans; D019751:Intramolecular Transferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008322:Mammals; D008969:Molecular Sequence Data; D010944:Plants / Q000201:enzymology; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
chemical_list: D018076:DNA, Complementary; D011994:Recombinant Proteins; D019751:Intramolecular Transferases; C021923:cycloartenol synthase