Isolation and characterization of two differentially regulated tryptophan decarboxylase (TDC) genes from Camptotheca acuminata (Decaisne) /
Camptothecin (CPT) is a valuable anti-cancer monoterpene alkaloid produced by the Chinese tree Camptotheca acuminata (Decaisne). Tryptophan decarboxylase (TDC) supplies tryptamine for the indole moiety of CPT and its derivatives, and is considered a key step in monoterpene indole alkaloid biosynthe...
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| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
1996.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739669491&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Camptothecin (CPT) is a valuable anti-cancer monoterpene alkaloid produced by the Chinese tree Camptotheca acuminata (Decaisne). Tryptophan decarboxylase (TDC) supplies tryptamine for the indole moiety of CPT and its derivatives, and is considered a key step in monoterpene indole alkaloid biosynthesis as it links primary and secondary metabolism. This dissertation describes the isolation and characterization of tdc1 and tdc2, two autonomously regulated TDC genes from C. acuminata. When expressed in Escherichia coli the products of each gene could decarboxylate tryptophan, but were inactive against tyrosine, phenylalanine, and DOPA. tdc1 was developmentally regulated, having its highest expression level in the apex, young stem and bark, tissues which also contain the highest levels of CPT. Expression of tdc1 also increased during seedling development and was correlated with alkaloid accumulation during germination. tdc2 expression was induced in C. acuminata leaf discs and cell suspension cultures treated with fungal elicitor or methyl jasmonate (MeJa), treatments which did not affect tdc1 expression. Unlike tdc1, tdc2 expression was not detected in any unstressed C. acuminata tissues nor in developing seedlings. These data suggest that tdc1 may be part of a developmental regulated chemical defense system in C. acuminata, while tdc2 serves as part of a defense system induced during pathogen challenge. |
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| Item Description: | Vita. "Major Subject: Biology". |
| Physical Description: | xi, 90 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 73-89. |