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Title: Regulation of terpene metabolism. Final technical report, March 15, 1988--March 14, 1996

Abstract

This research focuses on the following topics: the biosynthesis and catabolism of monoterpenes; the organization of monoterpene metabolism; the developmental regulation of monoterpene metabolism; the flux control of precursor supply; and the integration of monoterpene and higher terpenoid metabolism.

Authors:
Publication Date:
Research Org.:
Washington State Univ., Inst. of Biological Chemistry, Pullman, WA (United States)
Sponsoring Org.:
USDOE Office of Energy Research, Washington, DC (United States)
OSTI Identifier:
296879
Report Number(s):
DOE/ER/13869-T1
ON: DE99001286; TRN: AHC29903%%277
DOE Contract Number:
FG06-88ER13869
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: [1996]
Country of Publication:
United States
Language:
English
Subject:
56 BIOLOGY AND MEDICINE, APPLIED STUDIES; PROGRESS REPORT; BIOSYNTHESIS; METABOLISM; TERPENES; BIOLOGICAL PATHWAYS

Citation Formats

Croteau, R. Regulation of terpene metabolism. Final technical report, March 15, 1988--March 14, 1996. United States: N. p., 1996. Web. doi:10.2172/296879.
Croteau, R. Regulation of terpene metabolism. Final technical report, March 15, 1988--March 14, 1996. United States. doi:10.2172/296879.
Croteau, R. 1996. "Regulation of terpene metabolism. Final technical report, March 15, 1988--March 14, 1996". United States. doi:10.2172/296879. https://www.osti.gov/servlets/purl/296879.
@article{osti_296879,
title = {Regulation of terpene metabolism. Final technical report, March 15, 1988--March 14, 1996},
author = {Croteau, R.},
abstractNote = {This research focuses on the following topics: the biosynthesis and catabolism of monoterpenes; the organization of monoterpene metabolism; the developmental regulation of monoterpene metabolism; the flux control of precursor supply; and the integration of monoterpene and higher terpenoid metabolism.},
doi = {10.2172/296879},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1996,
month =
}

Technical Report:

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  • Progress in understanding of the metabolism of monoterpenes by peppermint and spearmint is recorded including the actions of two key enzymes, geranyl pyrophosphate:limonene cyclase and a UDP-glucose dependent glucosyl transferase; concerning the ultrastructure of oil gland senescence; enzyme subcellular localization; regulation of metabolism; and tissue culture systems.
  • Many lines of evidence suggest that the cyclases ((+){minus}bornyl pyrophosphate cyclases and ({minus}){minus}limonene cyclases) catalyze the rate-limiting steps of monoterpene biosynthesis in sage and mint, respectively. Similar evidence indicates that camphor hydroxylase, and the reductases that control the disposition of methone, are the critical steps of monoterpene catabolism in these systems. Related studies, based on in vitro assay of enzyme activities, have suggested that the accumulation and the compartmentation of these processes. Further studies directed toward localizing the pathways and determining the relevant protein and transcript levels require pure enzymes for antibody preparation and amino determining the relevant protein andmore » transcript levels require pure enzymes for antibody preparation and amino acid sequence determination.« less
  • This report describes accomplishments over the past year on understanding of terpene synthesis in mint plants and sage. Specifically reported are the fractionation of 4-S-limonene synthetase, the enzyme responsible for the first committed step to monoterpene synthesis, along with isolation of the corresponding RNA and DNA cloning of its gene; the localization of the enzyme within the oil glands, regulation of transcription and translation of the synthetase, the pathway to camphor biosynthesis,a nd studies on the early stages and branch points of the isoprenoid pathway.
  • During the last grant period, we have completed studies on the key pathways of monoterpene biosynthesis and catabolism in sage and peppermint, and have, by several lines of evidence, deciphered the rate-limiting step of each pathway. We have at least partially purified and characterized the relevant enzymes of each pathway. We have made a strong case, based on analytical, in vivo, and in vitro studies, that terpene accumulation depends upon the balance between biosynthesis and catabolism, and provided supporting evidence that these processes are developmentally-regulated and very closely associated with senescence of the oil glands. Oil gland ontogeny has beenmore » characterized at the ultrastructural level. We have exploited foliar-applied bioregulators to delay gland senescence, and have developed tissue explant and cell culture systems to study several elusive aspects of catabolism. We have isolated pure gland cell clusters and localized monoterpene biosynthesis and catabolism within these structures, and have used these preparations as starting materials for the purification to homogeneity of target ``regulatory`` enzymes. We have thus developed the necessary background knowledge, based on a firm understanding of enzymology, as well as the necessary experimental tools for studying the regulation of monoterpene metabolism at the molecular level. Furthermore, we are now in a position to extend our systematic approach to other terpenoid classes (C{sub 15}-C{sub 30}) produced by oil glands.« less
  • Terpenoid oils, resins, and waxes from plants are important renewable resources. The objective of this project is to understand the regulation of terpenoid metabolism using the monoterpenes (C{sub 10}) as a model. The pathways of monoterpene biosynthesis and catabolism have been established, and the relevant enzymes characterized. Developmental studies relating enzyme levels to terpene accumulation within the oil gland sites of synthesis, and work with bioregulators, indicate that monoterpene production is controlled by terpene cyclases, the enzymes catalyzing the first step of the monoterpene pathway. As the leaf oil glands mature, cyclase levels decline and monoterpene biosynthesis ceases. Yield thenmore » decreases as the monoterpenes undergo catabolism by a process involving conversion to a glycoside and transport from the leaf glands to the root. At this site, the terpenoid is oxidatively degraded to acetate that is recycled into other lipid metabolites. During the transition from terpene biosynthesis to catabolism, the oil glands undergo dramatic ultrastructural modification. Degradation of the producing cells results in mixing of previously compartmentized monoterpenes with the catabolic enzymes, ultimately leading to yield decline. This regulatory model is being applied to the formation of other terpenoid classes (C{sub 15} C{sub 20}, C{sub 30}, C{sub 40}) within the oil glands. Preliminary investigations on the formation of sesquiterpenes (C{sub 15}) suggest that the corresponding cyclases may play a lesser role in determining yield of these products, but that compartmentation effects are important. From these studies, a comprehensive scheme for the regulation of terpene metabolism is being constructed. Results from this project wail have important consequences for the yield and composition of terpenoid natural products that can be made available for industrial exploitation.« less