title: Molecular characterization of berberine bridge enzyme genes from opium poppy.
abstract: In Papaver somniferum (opium poppy) and related species, (S)-reticuline serves as a branch-point intermediate in the biosynthesis of numerous isoquinoline alkaloids. The berberine bridge enzyme (BBE) ([S]-reticuline:oxygen oxidoreductase [methylene bridge forming], EC 1.5.3.9) catalyzes the stereospecific conversion of the N-methyl moiety of (S)-reticuline into the berberine bridge carbon of (S)-scoulerine and represents the first committed step in the pathway leading to the antimicrobial alkaloid sanguinarine. Three unique genomic clones (bbe1, bbe2, and bbe3) similar to a BBE cDNA from Eschscholtzia californica (California poppy) were isolated from opium poppy. Two clones (bbe2 and bbe3) contained frame-shift mutations of which bbe2 was identified as a putative, nonexpressed pseudogene by RNA blot hybridization using a gene-specific probe and by the lack of transient expression of a chimeric gene fusion between the bbe2 5' flanking region and a beta-glucuronidase reporter gene. Similarly, bbe1 was shown to be expressed in opium poppy plants and cultured cells. Genomic DNA blot-hybridization data were consistent with a limited number of bbe homologs. RNA blot hybridization showed that bbe genes are expressed in roots and stems of mature plants and in seedlings within 3 d after germination. Rapid and transient BBE mRNA accumulation also occurred after treatment with a fungal elicitor or with methyl jasmonate. However, sanguinarine was found only in roots, seedlings, and fungal elicitor-treated cell cultures.
authors.affiliation: Department of Biological Sciences, University of Calgary, Alberta, Canada. pfacchin@acs.ucalgary.ca
authors.forename: P J
authors.initials: PJ
authors.lastname: Facchini
authors.forename: C
authors.initials: C
authors.lastname: Penzes
authors.forename: A G
authors.initials: AG
authors.lastname: Johnson
authors.forename: D
authors.initials: D
authors.lastname: Bull
mesh_terms: D000595:Amino Acid Sequence; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D008969:Molecular Sequence Data; D010089:Oxidoreductases, N-Demethylating / Q000235:genetics*; D010944:Plants / Q000201:enzymology*; D017386:Sequence Homology, Amino Acid
chemical_list: C071690:reticuline oxidase; D010089:Oxidoreductases, N-Demethylating