A chloroplastic UDP-glucose pyrophosphorylase from Arabidopsis is the committed enzyme for the first step of sulfolipid biosynthesis.
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.
Okazaki
Yozo
Y
RIKEN Plant Science Center, Tsurumi-ku, Yokohama 230-0045, Japan.
Shimojima
Mie
M
Sawada
Yuji
Y
Toyooka
Kiminori
K
Narisawa
Tomoko
T
Mochida
Keiichi
K
Tanaka
Hironori
H
Matsuda
Fumio
F
Hirai
Akiko
A
Hirai
Masami Yokota
MY
Ohta
Hiroyuki
H
Saito
Kazuki
K
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
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