title: Loss of Inositol Phosphorylceramide Sphingolipid Mannosylation Induces Plant Immune Responses and Reduces Cellulose Content in Arabidopsis.
abstract: Glycosylinositol phosphorylceramides (GIPCs) are a class of glycosylated sphingolipids found in plants, fungi, and protozoa. These lipids are abundant in the plant plasma membrane, forming ∼25% of total plasma membrane lipids. Little is known about the function of the glycosylated headgroup, but two recent studies have indicated that they play a key role in plant signaling and defense. Here, we show that a member of glycosyltransferase family 64, previously named ECTOPICALLY PARTING CELLS1, is likely a Golgi-localized GIPC-specific mannosyl-transferase, which we renamed GIPC MANNOSYL-TRANSFERASE1 (GMT1). Sphingolipid analysis revealed that the Arabidopsis thaliana gmt1 mutant almost completely lacks mannose-carrying GIPCs. Heterologous expression of GMT1 in Saccharomyces cerevisiae and tobacco (Nicotiana tabacum) cv Bright Yellow 2 resulted in the production of non-native mannosylated GIPCs. gmt1 displays a severe dwarfed phenotype and a constitutive hypersensitive response characterized by elevated salicylic acid and hydrogen peroxide levels, similar to that we previously reported for the Golgi-localized, GIPC-specific, GDP-Man transporter GONST1 (Mortimer et al., 2013). Unexpectedly, we show that gmt1 cell walls have a reduction in cellulose content, although other matrix polysaccharides are unchanged.
authors.affiliation: Joint BioEnergy Institute, Emeryville, California 94608.|Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, California 94720.
authors.forename: Lin
authors.identifier: 0000-0002-9971-4569
authors.initials: L
authors.lastname: Fang
authors.affiliation: Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Ishikawa
authors.affiliation: Joint BioEnergy Institute, Emeryville, California 94608.|Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, California 94720.
authors.forename: Emilie A
authors.initials: EA
authors.lastname: Rennie
authors.affiliation: Joint BioEnergy Institute, Emeryville, California 94608.|Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, California 94720.
authors.forename: Gosia M
authors.identifier: 0000-0003-1822-9607
authors.initials: GM
authors.lastname: Murawska
authors.affiliation: Joint BioEnergy Institute, Emeryville, California 94608.|Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, California 94720.
authors.forename: Jeemeng
authors.initials: J
authors.lastname: Lao
authors.affiliation: Joint BioEnergy Institute, Emeryville, California 94608.|Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, California 94720.
authors.forename: Jingwei
authors.initials: J
authors.lastname: Yan
authors.affiliation: Joint BioEnergy Institute, Emeryville, California 94608.|Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, California 94720.
authors.forename: Alex Yi-Lin
authors.initials: AY
authors.lastname: Tsai
authors.affiliation: Joint BioEnergy Institute, Emeryville, California 94608.|Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, California 94720.
authors.forename: Edward E K
authors.initials: EE
authors.lastname: Baidoo
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720.
authors.forename: Jun
authors.identifier: 0000-0003-3507-0159
authors.initials: J
authors.lastname: Xu
authors.affiliation: Joint BioEnergy Institute, Emeryville, California 94608.|Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, California 94720.|Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720.
authors.forename: Jay D
authors.identifier: 0000-0003-4170-6088
authors.initials: JD
authors.lastname: Keasling
authors.affiliation: Cellulose Production Research Team, Biomass Engineering Program, Center for Sustainable Resource Science, RIKEN, Yokohama 230-0045, Japan.|Graduate School of Biological Sciences, Nara Institute of Science and Technology, 630-0192 Nara, Japan.
authors.forename: Taku
authors.initials: T
authors.lastname: Demura
authors.affiliation: Graduate School of Science and Engineering, Saitama University, Saitama 338-8570, Japan.
authors.forename: Maki
authors.initials: M
authors.lastname: Kawai-Yamada
authors.affiliation: Joint BioEnergy Institute, Emeryville, California 94608.|Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, California 94720.|Plant and Microbial Biology, University of California, Berkeley, California 94720.
authors.forename: Henrik V
authors.identifier: 0000-0002-6702-3560
authors.initials: HV
authors.lastname: Scheller
authors.affiliation: Joint BioEnergy Institute, Emeryville, California 94608 jcmortimer@lbl.gov.|Biological Systems and Engineering, Lawrence Berkeley National Laboratory, Berkeley, California 94720.|Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720.
authors.forename: Jenny C
authors.identifier: 0000-0001-6624-636X
authors.initials: JC
authors.lastname: Mortimer
mesh_terms: D017360:Arabidopsis / Q000276:immunology* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism*; D006028:Glycosphingolipids / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D013107:Sphingolipids / Q000378:metabolism*; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C445096:GONST1 protein, Arabidopsis; D006028:Glycosphingolipids; D026901:Membrane Transport Proteins; D013107:Sphingolipids; C477937:inositolphosphorylceramide; D002482:Cellulose