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Lawrence Berkeley National Laboratory - A family of six nucleotide sugar transporters never before described have been characterized in Arabidopsis, a model plant for research in advanced biofuels. Photo by Roy Kaltschmidt
Scientist from the U.S. Department of Energy (DOE)’s Joint BioEnergy Institute (JBEI) have developed a new tool which can support the engineering of fuel crops for the production of clean, green and renewable bioenergy. The new development made by the team at JBEI represents significant potential for transportation fuels – gasoline, diesel and jet fuel - which may offer a competitive alternative to petroleum based fuels.
Led by Lawrence Berkeley National Laboratory (Berkeley Lab) the JBEI have developed an assay which will enable scientists to characterize the purpose of nucleotide sugar transporters. These transporters are crucial components in the biosynthesis of plant cell walls.
Our unique assay enabled us to analyze nucleotide sugar transporter activities in Arabidopsis and characterize a family of six nucleotide sugar transporters that has never before been described. Our method should enable rapid progress to be made in determining the functional role of nucleotide sugar transporters in plants and other organisms, which is very important for the metabolic engineering of cell walls.
Henrik Scheller, the leader of JBEI’s Feedstocks Division
The sugars found in the plants biomass hold huge potential for the production of environmentally benign energy. If successfully converted into transportation fuels it could offer companies and consumers an economically competitive alternative to petroleum based fuels.
One of the main obstacles facing the team is successfully engineering fuel crops with cell walls that are optimized for sugar content.
The complex polysaccharide sugars found in plant cell walls are made in the Golgi apparatus by enzymes called glycosyltransferases. Assembled from substrates of simple nucleotide sugars, these polysaccharides are transported into the Golgi apparatus from the cytosol, the gel-like liquid which fills a plants cell’s cytoplasm.
Although very important to the research, few plant nucleotide sugar transporters have been functionally characterized on a molecular level. A lack of substrates that are necessary to carry out such characterization have been a major factor in the slow progression of this technology.
"Substrates of mammalian nucleotide sugar transporters are commercially available because of the medical interest but have not been available for plants, which made it difficult to study both nucleotide sugar transporters and glycosyltransferases,” Scheller says.
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The Joint BioEnergy Institute (JBEI) is one of three Bioenergy Research Centers established by DOE’s Office of Science to accelerate the development of advanced, next-generation biofuels. Photo by Roy Kaltschmidt
For their assay the researchers synthesized several artificial substrates for nucleotide sugar transporters. These were then re-built into liposomes for analysis with mass spectrometry.
Using Arabidopsis, a relative of the mustard plant, the team were able to characterize the function of the six new nucleotide sugar transporters.
We found that these six new nucleotide sugar transporters are bispecific, which is a surprise since the two substrates are not very similar from a physical standpoint to the human eye. We also found that limiting substrate availability has different effects on different polysaccharide products, which suggests that cell wall polysaccharide biosynthesis in the Golgi apparatus of plants is also regulated by substrate transport mechanisms.
Henrik Scheller, the leader of JBEI’s Feedstocks Division
Looking to a Green Future
The research conducted by the team at JBEI represents a huge leap forward in biofuel technology and as a result they now know the activity of three times more nucleotide sugar transporters.
It may be some time before consumers have the option between bioenergy and petroleum based fuels at their local garage, but the research conducted by the team from JBEI could offer a new tool in the development of commercial competitive bio fuels.
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