title: Identification of a sphingolipid α-glucuronosyltransferase that is essential for pollen function in Arabidopsis.
abstract: Glycosyl inositol phosphorylceramide (GIPC) sphingolipids are a major class of lipids in fungi, protozoans, and plants. GIPCs are abundant in the plasma membrane in plants, comprising around a quarter of the total lipids in these membranes. Plant GIPCs contain unique glycan decorations that include a conserved glucuronic acid (GlcA) residue and various additional sugars; however, no proteins responsible for glycosylating GIPCs have been identified to date. Here, we show that the Arabidopsis thaliana protein INOSITOL PHOSPHORYLCERAMIDE GLUCURONOSYLTRANSFERASE1 (IPUT1) transfers GlcA from UDP-GlcA to GIPCs. To demonstrate IPUT1 activity, we introduced the IPUT1 gene together with genes for a UDP-glucose dehydrogenase from Arabidopsis and a human UDP-GlcA transporter into a yeast mutant deficient in the endogenous inositol phosphorylceramide (IPC) mannosyltransferase. In this engineered yeast strain, IPUT1 transferred GlcA to IPC. Overexpression or silencing of IPUT1 in Nicotiana benthamiana resulted in an increase or a decrease, respectively, in IPC glucuronosyltransferase activity in vitro. Plants in which IPUT1 was silenced accumulated IPC, the immediate precursor, as well as ceramides and glucosylceramides. Plants overexpressing IPUT1 showed an increased content of GIPCs. Mutations in IPUT1 are not transmitted through pollen, indicating that these sphingolipids are essential in plants.
authors.affiliation: Joint BioEnergy Institute, Emeryville, California 94608 Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 Department of Plant and Microbial Biology, University of California, Berkeley, California 94720.
authors.forename: Emilie A
authors.initials: EA
authors.lastname: Rennie
authors.affiliation: Joint BioEnergy Institute, Emeryville, California 94608 Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720.
authors.forename: Berit
authors.initials: B
authors.lastname: Ebert
authors.affiliation: Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom.
authors.forename: Godfrey P
authors.initials: GP
authors.lastname: Miles
authors.affiliation: Center for Plant Science Innovation and Department of Biochemistry, University of Nebraska, Lincoln, Nebraska 68588.
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: Cahoon
authors.affiliation: Joint BioEnergy Institute, Emeryville, California 94608 Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720.
authors.forename: Katy M
authors.initials: KM
authors.lastname: Christiansen
authors.affiliation: Joint BioEnergy Institute, Emeryville, California 94608 Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720.
authors.forename: Solomon
authors.initials: S
authors.lastname: Stonebloom
authors.affiliation: Center for Plant Science Innovation and Department of Biochemistry, University of Nebraska, Lincoln, Nebraska 68588.
authors.forename: Hoda
authors.initials: H
authors.lastname: Khatab
authors.affiliation: Department of Biology, University of Leicester, Leicester LE1 7RH, United Kingdom.
authors.forename: David
authors.initials: D
authors.lastname: Twell
authors.affiliation: Joint BioEnergy Institute, Emeryville, California 94608 Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Petzold
authors.affiliation: Joint BioEnergy Institute, Emeryville, California 94608 Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 Department of Bioengineering, University of California, Berkeley, California 94720.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Adams
authors.affiliation: Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: Dupree
authors.affiliation: Joint BioEnergy Institute, Emeryville, California 94608 Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720.
authors.forename: Joshua L
authors.initials: JL
authors.lastname: Heazlewood
authors.affiliation: Center for Plant Science Innovation and Department of Biochemistry, University of Nebraska, Lincoln, Nebraska 68588.
authors.forename: Edgar B
authors.initials: EB
authors.lastname: Cahoon
authors.affiliation: Joint BioEnergy Institute, Emeryville, California 94608 Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 Department of Plant and Microbial Biology, University of California, Berkeley, California 94720 hscheller@lbl.gov.
authors.forename: Henrik Vibe
authors.initials: HV
authors.lastname: Scheller
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020868:Gene Silencing; D020723:Glucuronic Acid / Q000378:metabolism*; D014453:Glucuronosyltransferase / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D011058:Pollen / Q000201:enzymology / Q000378:metabolism / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D013107:Sphingolipids / Q000378:metabolism*; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D013107:Sphingolipids; D020723:Glucuronic Acid; D014453:Glucuronosyltransferase; C000598949:IPUT1 protein, Arabidopsis