期刊
PHYTOCHEMISTRY
卷 69, 期 14, 页码 2539-2545出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.phytochem.2008.07.011
关键词
Parthenium argentatum; Guayule; Ficus elastica; Hevea brasiliensis; Photoaffinity labeling; Benzophenone; Allylic pyrophosphate; Farnesyl pyrophosphate; Rubber transferase; Cis-prenyltransferase
资金
- National Science Foundation Plant Genome Research [DBI 0321690]
- Functional Identification of Rubber Biosynthetic Genes
- Crop Plants and Bioreactors, USDA-CSREES-IFAFS [5325-41000-019-05R]
Natural rubber, cis-1,4-polyisoprene, is a vital industrial material synthesized by plants via a side branch of the isoprenoid pathway by the enzyme rubber transferase. While the specific structure of this enzyme is not yet defined, based on activity it is probably a cis-prenyl transferase. Photoactive functionalized substrate analogues have been successfully used to identify isoprenoid-utilizing enzymes such as cis- and trans-prenyltransferases, and initiator binding of an allylic pyrophosphate molecule in rubber transferase has similar features to these systems. In this paper, a series of benzophenone-modified initiator analogues were shown to successfully initiate rubber biosynthesis in vitro in enzymatically-active washed rubber particles from Ficus elastica, Hevea brasiliensis and Parthenium argentatum. Rubber transferases from all three species initiated rubber biosynthesis most efficiently with farnesyl pyrophosphate. However, rubber transferase had a higher affinity for benzophenone geranyl pyrophosphate (Bz-GPP) and dimethylallyl pyrophosphate (Bz-DMAPP) analogues with ether-linkages than the corresponding GPP or DMAPP. In contrast, ester-linked Bz-DMAPP analogues were less efficient initiators than DMAPP. Thus, rubber biosynthesis depends on both the size and the structure of Bz-initiator molecules. Kinetic studies thereby inform selection of specific probes for covalent photolabeling of the initiator binding site of rubber transferase. Published by Elsevier Ltd.
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