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Plant Cell. 2012 Mar;24(3):1202-16. doi: 10.1105/tpc.112.095885. Epub 2012 Mar 13.

Lysine decarboxylase catalyzes the first step of quinolizidine alkaloid biosynthesis and coevolved with alkaloid production in leguminosae.

Author information

1
Graduate School of Pharmaceutical Sciences, Chiba University, Chuo-ku, Chiba 260-8675, Japan.

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.

PMID:
22415272
PMCID:
PMC3336119
DOI:
10.1105/tpc.112.095885
[Indexed for MEDLINE]
Free PMC Article

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