title: Loss of hydroxyl groups from the ceramide moiety can modify the lateral diffusion of membrane proteins in S. cerevisiae.
abstract: In the yeast Saccharomyces cerevisiae, structural diversities of complex sphingolipids [inositol phosphorylceramide (IPC), mannosylinositol phosphorylceramide, and mannosyldiinositol phosphorylceramide] are often observed in the presence or absence of hydroxyl groups on the C-4 position of long-chain base (C4-OH) and the C-2 position of very long-chain fatty acids (C2-OH), but the biological significance of these groups remains unclear. Here, we evaluated cellular membrane fluidity in hydroxyl group-defective yeast mutants by fluorescence recovery after photobleaching. The lateral diffusion of enhanced green fluorescent protein-tagged hexose transporter 1 (Hxt1-EGFP) was influenced by the absence of C4-OH and/or C2-OH. Notably, the fluorescence recovery of Hxt1-EGFP was dramatically decreased in the sur2Δ mutant (absence of C4-OH) under the csg1Δcsh1Δ background, in which mannosylation of IPC is blocked leading to IPC accumulation, while the recovery in the scs7Δ mutant (absence of C2-OH) under the same background was modestly decreased. In addition, the amount of low affinity tryptophan transporter 1 (Tat1)-EGFP was markedly decreased in the sur2Δcsg1Δcsh1Δ mutant and accumulated in intracellular membranes in the scs7Δcsg1Δcsh1Δ mutant without altering its protein expression. These results suggest that C4-OH and C2-OH are most probably critical factors for maintaining membrane fluidity and proper turnover of membrane molecules in yeast containing complex sphingolipids with only one hydrophilic head group.
authors.affiliation: Division of Glycopathology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Pharmaceutical University, Sendai 981-8558, Japan Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, Sagamihara 252-5258, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Uemura
authors.affiliation: Division of Glycopathology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Pharmaceutical University, Sendai 981-8558, Japan.
authors.forename: Fumi
authors.initials: F
authors.lastname: Shishido
authors.affiliation: Department of Chemistry, Kyushu University, Fukuoka 812-8581, Japan.
authors.forename: Motohiro
authors.initials: M
authors.lastname: Tani
authors.affiliation: Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, Sagamihara 252-5258, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Mochizuki
authors.affiliation: Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, Sagamihara 252-5258, Japan Institute of Biogeosciences, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka 237-0061, Japan.
authors.forename: Fumiyoshi
authors.initials: F
authors.lastname: Abe
authors.affiliation: Division of Glycopathology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Pharmaceutical University, Sendai 981-8558, Japan.
authors.forename: Jin-Ichi
authors.initials: J
authors.lastname: Inokuchi
mesh_terms: D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D002518:Ceramides / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D002518:Ceramides; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; D006899:Mixed Function Oxygenases; C109313:SUR2 protein, S cerevisiae
keywords: Saccharomyces cerevisiae; fluorescence recovery after photobleaching; glycolipids; hydroxyl group; lipid rafts; membranes/fluidity; sphingolipids; yeast