title: Lysine decarboxylase catalyzes the first step of quinolizidine alkaloid biosynthesis and coevolved with alkaloid production in leguminosae.
abstract: Lysine decarboxylase (LDC) catalyzes the first-step in the biosynthetic pathway of quinolizidine alkaloids (QAs), which form a distinct, large family of plant alkaloids. A cDNA of lysine/ornithine decarboxylase (L/ODC) was isolated by differential transcript screening in QA-producing and nonproducing cultivars of Lupinus angustifolius. We also obtained L/ODC cDNAs from four other QA-producing plants, Sophora flavescens, Echinosophora koreensis, Thermopsis chinensis, and Baptisia australis. These L/ODCs form a phylogenetically distinct subclade in the family of plant ornithine decarboxylases. Recombinant L/ODCs from QA-producing plants preferentially or equally catalyzed the decarboxylation of L-lysine and L-ornithine. L. angustifolius L/ODC (La-L/ODC) was found to be localized in chloroplasts, as suggested by the transient expression of a fusion protein of La-L/ODC fused to the N terminus of green fluorescent protein in Arabidopsis thaliana. Transgenic tobacco (Nicotiana tabacum) suspension cells and hairy roots produced enhanced levels of cadaverine-derived alkaloids, and transgenic Arabidopsis plants expressing (La-L/ODC) produced enhanced levels of cadaverine, indicating the involvement of this enzyme in lysine decarboxylation to form cadaverine. Site-directed mutagenesis and protein modeling studies revealed a structural basis for preferential LDC activity, suggesting an evolutionary implication of L/ODC in the QA-producing plants.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Chiba University, Chuo-ku, Chiba 260-8675, Japan.
authors.forename: Somnuk
authors.initials: S
authors.lastname: Bunsupa
authors.forename: Kae
authors.initials: K
authors.lastname: Katayama
authors.forename: Emi
authors.initials: E
authors.lastname: Ikeura
authors.forename: Akira
authors.initials: A
authors.lastname: Oikawa
authors.forename: Kiminori
authors.initials: K
authors.lastname: Toyooka
authors.forename: Kazuki
authors.initials: K
authors.lastname: Saito
authors.forename: Mami
authors.initials: M
authors.lastname: Yamazaki
mesh_terms: D000470:Alkaloids / Q000096:biosynthesis*; D017360:Arabidopsis / Q000378:metabolism; D002103:Cadaverine / Q000378:metabolism; D002262:Carboxy-Lyases / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000201:enzymology; D003001:Cloning, Molecular; D003653:Decarboxylation; D031297:Lupinus / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009955:Ornithine Decarboxylase / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D054837:Quinolizidines / Q000378:metabolism*; D013379:Substrate Specificity; D014026:Nicotiana / Q000378:metabolism
chemical_list: D000470:Alkaloids; D010940:Plant Proteins; D054837:Quinolizidines; D002262:Carboxy-Lyases; D009955:Ornithine Decarboxylase; C021520:lysine decarboxylase; D002103:Cadaverine