title: Structural characterization of suppressor lipids by high-resolution mass spectrometry.
abstract: BACKGROUND
  Suppressor lipids were originally identified in 1993 and reported to encompass six lipid classes that enable Saccharomyces cerevisiae to live without sphingolipids. Structural characterization, using non-mass spectrometric approaches, revealed that these suppressor lipids are very long chain fatty acid (VLCFA)-containing glycerophospholipids with polar head groups that are typically incorporated into sphingolipids. Here we report, for the first time, the structural characterization of the yeast suppressor lipids using high-resolution mass spectrometry.
  
  
  METHODS
  Suppressor lipids were isolated by preparative chromatography and subjected to structural characterization using hybrid quadrupole time-of-flight and ion trap-orbitrap mass spectrometry.
  
  
  RESULTS
  Our investigation recapitulates the overall structural features of the suppressor lipids and provides an in-depth characterization of their fragmentation pathways. Tandem mass analysis identified the positionally defined molecular lipid species phosphatidylinositol (PI) 26:0/16:1, PI mannoside (PIM) 16:0/26:0 and PIM inositol-phosphate (PIMIP) 16:0/26:0 as abundant suppressor lipids. This finding differs from the original study that only inferred the positional isomer PI 16:0/26:0 and prompts new insight into the biosynthesis of suppressor lipids. Moreover, we also report the identification of a novel suppressor lipid featuring an amino sugar residue linked to a VLCFA-containing PI molecule.
  
  
  CONCLUSIONS
  Fragmentation pathways of yeast suppressor lipids have been delineated. In addition, the fragmentation information has been added to our open source ALEX lipid database to support automated identification and quantitative monitoring of suppressor lipids in yeast and bacteria that produce similar lipid molecules. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark.
authors.forename: Mary Joy
authors.initials: MJ
authors.lastname: Rovillos
authors.affiliation: Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark.
authors.forename: Josch Konstantin
authors.initials: JK
authors.lastname: Pauling
authors.affiliation: Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark.
authors.forename: Hans Kristian
authors.initials: HK
authors.lastname: Hannibal-Bach
authors.affiliation: Division of Biochemistry, Department of Biology, University of Fribourg, Fribourg, Switzerland.
authors.forename: Christine
authors.initials: C
authors.lastname: Vionnet
authors.affiliation: Division of Biochemistry, Department of Biology, University of Fribourg, Fribourg, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Conzelmann
authors.affiliation: Department of Biochemistry and Molecular Biology, VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, Odense, Denmark. cse@bmb.sdu.dk.
authors.forename: Christer S
authors.initials: CS
authors.lastname: Ejsing
mesh_terms: D005227:Fatty Acids / Q000737:chemistry* / Q000378:metabolism; D020404:Glycerophospholipids / Q000737:chemistry* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000737:chemistry* / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D005227:Fatty Acids; D020404:Glycerophospholipids