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Sample Set Information

ID TSE1304
Title A chloroplastic UDP-glucose pyrophosphorylase from Arabidopsis is the committed enzyme for the first step of sulfolipid biosynthesis.
Description Plants synthesize a sulfur-containing lipid, sulfoquinovosyldiacylglycerol, which is one of three nonphosphorus glycerolipids that provide the bulk of the structural lipids in photosynthetic membranes. Here, the identification of a novel gene, UDP-glucose pyrophosphorylase3 (UGP3), required for sulfolipid biosynthesis is described. Transcriptome coexpression analysis demonstrated highly correlated expression of UGP3 with known genes for sulfolipid biosynthesis in Arabidopsis thaliana. Liquid chromatography-mass spectrometry analysis of leaf lipids in two Arabidopsis ugp3 mutants revealed that no sulfolipid was accumulated in these mutants, indicating the participation of UGP3 in sulfolipid biosynthesis. From the deduced amino acid sequence, UGP3 was presumed to be a UDP-glucose pyrophosphorylase (UGPase) involved in the generation of UDP-glucose, serving as the precursor of the polar head of sulfolipid. Recombinant UGP3 was able to catalyze the formation of UDP-glucose from glucose-1-phosphate and UTP. A transient assay using fluorescence fusion proteins and UGPase activity in isolated chloroplasts indicated chloroplastic localization of UGP3. The transcription level of UGP3 was increased by phosphate starvation. A comparative genomics study on UGP3 homologs across different plant species suggested the structural and functional conservation of the proteins and, thus, a committing role for UGP3 in sulfolipid synthesis.
Authors Okazaki Y, Shimojima M, Sawada Y, Toyooka K, Narisawa T, Mochida K, Tanaka H, Matsuda F, Hirai A, Hirai MY, Ohta H, Saito K.
Reference Plant Cell. 2009 Mar;21(3):892-909. doi: 10.1105/tpc.108.063925. Epub 2009 Mar 13.

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Analytical Method Details Information

Title Analysis of UDP-Glc in Arabidopsis Leaves
Instrument UPLC-Q-MS
Instrument Type
Ionization ESI
Ion Mode positive and negative
Description Rosette leaves of Arabidopsis (250 mg fresh weight) grown in soil were frozen in liquid nitrogen and homogenized to a fine powder using a mortar and pestle. The powder was extracted with 2.5 mL of 50% (v/v) methanol and subjected to UPLC-Q-MS analysis (flow rate, 0.3 mL min−1; column, ACQUITY UPLC HSS T3 1.8 μm [2.1 mm i.d., 50 mm long; Waters]; solvent, 10 mM triethylamine acetate, pH 6.0; column temperature, 30°C; conditions for MS were same as those used for assay of recombinant UGP3) (Ramm et al., 2004).

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