New Tool for Plants May Help Create 'Fuel' Crops for Bioenergy

Could there be a new way to advance genetic engineering? Scientists have created a new tool that could potentially help create "fuel" crops for clean, renewable bioenergy--an assay that allows scientists to identify and characterize the function of nucleotide sugar transporters.

Sugars in plant biomass represent a huge potential source of environmentally benign energy if they can be converted into transportation fuels in a way that is economically competitive with petroleum-based fuels. A way to do this is harvesting crops that have been engineered for optimized sugar content.

With the exception of cellulose and callose, the polysaccharide sugars in plant walls are synthesized in the Golgi apparatus by enzymes called glycosyltransferases. The polysaccharides in turn are assembled from substrates of simple nucleotide sugars which are transported into the Golgi apparatus from the cytosol. Part of the reason why so few plant nucleotide sugar transporters have been characterized at the molecular level has been due to the fact that there's been a lack of substrates necessary to carry out these interactions.

 In this study, the researchers created several artificial substrates for nucleotide sugar transporters for their assay. Then, they reconstituted the transporters into liposomes for analysis with mass spectrometry. This allowed them to characterize the functions of six new nucleotide sugar transporters that they identified in the plant, Arabidopsis.

"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," said Henrik Scheller, one of the researchers, in a news release. "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."

More specifically, the researchers found that the six new nucleotide sugars were bispecific. In addition, they found that limiting substrate availability has different effects on different polysaccharide products.

The findings are published in the journal Proceedings of the National Academy of Sciences.