Initiation of rubber biosynthesis: In vitro comparisons of benzophenone-modified diphosphate analogues in three rubber-producing species

Wenshuang Xie, Colleen M. McMahan, Amanda J. DeGraw, Mark D. Distefano, Katrina Cornish, Maureen C. Whalen, David K. Shintani

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)2539-2545
Number of pages7
JournalPhytochemistry
Volume69
Issue number14
DOIs
StatePublished - Oct 2008

Bibliographical note

Funding Information:
We thank Drs. James Thompson and Christopher Mau for their critical review of this manuscript. We acknowledge Dr. Deborah Scott for helpful suggestions. Ms. De Wood of USDA-ARS provided the beautiful electron micrograph of the washed rubber particle. Dr. Terry Coffelt of USDA-ARS-USALARC kindly provided P. argentatum materials for the washed rubber particle isolation, and Dr. R. Krishnakumar the H. brasiliensis washed rubber particles. This work was supported by the National Science Foundation Plant Genome Research Program DBI 0321690, Functional Identification of Rubber Biosynthetic Genes, and by the 5325-41000-019-05R “Commercial and Strategic Rubber from Crop Plants and Bioreactors”, USDA-CSREES-IFAFS.

Keywords

  • Allylic pyrophosphate
  • Benzophenone
  • Cis-prenyltransferase
  • Farnesyl pyrophosphate
  • Ficus elastica
  • Guayule
  • Hevea brasiliensis
  • Parthenium argentatum
  • Photoaffinity labeling
  • Rubber transferase

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