DEVELOPMENT OF DOMESTIC NATURAL RUBBER-PRODUCING INDUSTRIAL CROPS THROUGH BIOTECHNOLOGY
Location: Crop Improvement & Utilization Research
Title: The functional analyses of the cis-prenyltransferase and the rubber elongation factor in rubber biosynthesis
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 27, 2009
Publication Date: May 25, 2009
Citation: Shintani, D., Collins, J., Distefano, M., Hathwaik, U., Henry, O., Mcmahan, C.M., Whalen, M.C., Xie, W. 2009. The functional analyses of the cis-prenyltransferase and the rubber elongation factor in rubber biosynthesis. Terpnet 2009.
Natural rubber (cis-1,4-polyisoprene) is an essential plant derived commodity required for the manufacture of numerous industrial, medical and household items. Rubber is synthesized and sequestered on cytsolic vesicles known as rubber particles. When provided with farnesyl pyrophosphate (FPP) and isopentenyl pyrophosphate, rubber particles are alone sufficient for rubber biosynthesis. Surprisingly, although this process has been studied for over 50 years, due to the labile nature of the rubber transferase, the identification its protein subunits remain elusive. To address this issue, we conducted a series of photoaffinity tagging experiments on active Hevea brasiliensis (Hevea) rubber particles using benzophenone FPP analogs. From these studies we have identified two candidate rubber transferase protein subunits, specifically the rubber elongation factor (REF) and the cis-prenyltransferase (CPT). To functionally test the role of these two proteins in rubber biosynthesis, reverse genetic studies were performed in Taraxacum kok-saghyz (TKS). In these studies genes encoding TKS orthologs of the Hevea REF and CPT were over- and under-expressed in transgenic TKS. Results from the REF studies showed that TKS REF gene expression levels directly correlate with amount and the molecular weight of the rubber produced, supporting this proteins hypothesized role in rubber biosynthesis. TKS CPT reverse genetic studies are ongoing with the over- and under-expressing CPT lines currently in tissue culture.