Journal Article

Camptothecin Biosynthetic Genes in Hairy Roots of <i>Ophiorrhiza pumila</i>: Cloning, Characterization and Differential Expression in Tissues and by Stress Compounds

Yasuyo Yamazaki, Hiroshi Sudo, Mami Yamazaki, Norio Aimi and Kazuki Saito

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 44, issue 4, pages 395-403
Published in print April 2003 | ISSN: 0032-0781
Published online April 2003 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcg051
Camptothecin Biosynthetic Genes in Hairy Roots of Ophiorrhiza pumila: Cloning, Characterization and Differential Expression in Tissues and by Stress Compounds

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Camptothecin derivatives are clinically used anti-tumor compounds that biogenetically belong to a group of monoterpenoid indole alkaloids (TIA). We have already established a hairy root culture of Ophiorrhiza pumila (Rubiaceae) that produces camptothecin. The present study describes the cloning and characterization of cDNAs encoding strictosidine synthase (OpSTR; EC 4.3.3.2) and tryptophan decarboxylase (OpTDC; EC 4.1.1.28), two key enzymes in the biosynthesis of TIA from hairy roots of O. pumila. We also isolated the cDNA coding for NADPH:cytochrome P450 reductase (OpCPR; EC 1.6.2.4) that is presumed to be indirectly involved in camptothecin synthesis. The recombinant OpSTR and OpTDC proteins exhibit STR and TDC activities, respectively, when expressed in Escherichia coli. The tissue-specific and stress-inducible expression patterns of OpSTR and OpTDC were quite similar, unlike those of OpCPR. The high expression of OpSTR and OpTDC observed in hairy roots, roots and stems were closely correlated with STR protein accumulation as observed by immunoblot analysis. Plant stress compounds like salicylic acid repressed expression of OpSTR and OpTDC, suggesting coordinate regulation of these genes for camptothecin biosynthesis.

Keywords: Keywords: Anti-tumor alkaloid — Camptothecin — NADPH:cytochrome P450 reductase — Ophiorrhiza pumila — Strictosidine synthase — Tryptophan decarboxylase.; The nucleotide sequences in this paper have been submitted to DDBJ/GenBank/EMBL under accession numbers AB060341 (OpSTR), AB086168 (OpTDC) and AB086169 (OpCPR).

Journal Article.  6744 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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