Abstract
We established a platform to analyze a wide range of plant lipids based on liquid chromatography mass spectrometry, and utilized for analysis of lipidome of Arabidopsis T-DNA insertion lines to identify new lipid metabolic genes. To narrow down the new genes involved in the lipid metabolism, we analyzed transcriptional network of genes involved in the lipid metabolism in Arabidopsis, and we prioritized a previously-uncharacterized gene (UGP3) highly coexpressed with known glycoglycerolipid biosynthetic genes. Profiling of leaf lipids in the knockout mutants of this candidate gene revealed that no sulfolipid was accumulated in these mutants, indicating the participation of UGP3 in sulfolipid biosynthesis. Recombinant UGP3 was able to catalyze the formation of UDP-glucose from glucose-1-phosphate and UTP. A transient assay using fluorescence-fusion proteins indicated chloroplastic localization of UGP3. These results indicated that UGP3 was chloroplastic UDP-glucose pyrophosphorylase involved in the biosynthesis of UDP-glucose, the precursor of UDP-sulfoquinovose for sulfolipid biosynthesis.
