title: A chloroplastic UDP-glucose pyrophosphorylase from Arabidopsis is the committed enzyme for the first step of sulfolipid biosynthesis.
abstract: 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.affiliation: RIKEN Plant Science Center, Tsurumi-ku, Yokohama 230-0045, Japan.
authors.forename: Yozo
authors.initials: Y
authors.lastname: Okazaki
authors.forename: Mie
authors.initials: M
authors.lastname: Shimojima
authors.forename: Yuji
authors.initials: Y
authors.lastname: Sawada
authors.forename: Kiminori
authors.initials: K
authors.lastname: Toyooka
authors.forename: Tomoko
authors.initials: T
authors.lastname: Narisawa
authors.forename: Keiichi
authors.initials: K
authors.lastname: Mochida
authors.forename: Hironori
authors.initials: H
authors.lastname: Tanaka
authors.forename: Fumio
authors.initials: F
authors.lastname: Matsuda
authors.forename: Akiko
authors.initials: A
authors.lastname: Hirai
authors.forename: Masami Yokota
authors.initials: MY
authors.lastname: Hirai
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ohta
authors.forename: Kazuki
authors.initials: K
authors.lastname: Saito
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology; D029681:Arabidopsis Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000378:metabolism; D019143:Evolution, Molecular; D038983:Galactolipids / Q000096:biosynthesis / Q000737:chemistry; D018506:Gene Expression Regulation, Plant; D006017:Glycolipids / Q000096:biosynthesis / Q000737:chemistry; D006602:Hexosyltransferases / Q000235:genetics / Q000378:metabolism; D007527:Isoenzymes / Q000145:classification / Q000378:metabolism*; D008055:Lipids / Q000096:biosynthesis / Q000737:chemistry; D015394:Molecular Structure; D009154:Mutation; D010710:Phosphates / Q000378:metabolism; D010802:Phylogeny; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013431:Sulfates / Q000378:metabolism; D005957:UTP-Glucose-1-Phosphate Uridylyltransferase / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D014532:Uridine Diphosphate Glucose / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D004791:Enzyme Inhibitors; D038983:Galactolipids; D006017:Glycolipids; D007527:Isoenzymes; D008055:Lipids; D010710:Phosphates; D011993:Recombinant Fusion Proteins; C110849:SQD1 protein, Arabidopsis; D013431:Sulfates; C015518:sulfolipids; C013694:sulfoquinovosyl diglyceride; D006602:Hexosyltransferases; C456289:SQD2 protein, Arabidopsis; D005957:UTP-Glucose-1-Phosphate Uridylyltransferase; D014532:Uridine Diphosphate Glucose