title: Phosphatidylcholine Supply to Peroxisomes of the Yeast Saccharomyces cerevisiae.
abstract: In the yeast Saccharomyces cerevisiae, phosphatidylcholine (PC), the major phospholipid (PL) of all organelle membranes, is synthesized via two different pathways. Methylation of phosphatidylethanolamine (PE) catalyzed by the methyl transferases Cho2p/Pem1p and Opi3p/Pem2p as well as incorporation of choline through the CDP (cytidine diphosphate)-choline branch of the Kennedy pathway lead to PC formation. To determine the contribution of these two pathways to the supply of PC to peroxisomes (PX), yeast mutants bearing defects in the two pathways were cultivated under peroxisome inducing conditions, i.e. in the presence of oleic acid, and subjected to biochemical and cell biological analyses. Phenotype studies revealed compromised growth of both the cho20Δopi3Δ (mutations in the methylation pathway) and the cki1Δdpl1Δeki1Δ (mutations in the CDP-choline pathway) mutant when grown on oleic acid. Analysis of peroxisomes from the two mutant strains showed that both pathways produce PC for the supply to peroxisomes, although the CDP-choline pathway seemed to contribute with higher efficiency than the methylation pathway. Changes in the peroxisomal lipid pattern of mutants caused by defects in the PC biosynthetic pathways resulted in changes of membrane properties as shown by anisotropy measurements with fluorescent probes. In summary, our data define the origin of peroxisomal PC and demonstrate the importance of PC for peroxisome membrane formation and integrity.
authors.affiliation: Institute of Biochemistry, Graz University of Technology, NAWI Graz, Graz, Austria.
authors.forename: Vid V
authors.initials: VV
authors.lastname: Flis
authors.affiliation: Institute of Biochemistry, Graz University of Technology, NAWI Graz, Graz, Austria.
authors.forename: Ariane
authors.initials: A
authors.lastname: Fankl
authors.affiliation: Institute of Biochemistry, Graz University of Technology, NAWI Graz, Graz, Austria.
authors.forename: Claudia
authors.initials: C
authors.lastname: Ramprecht
authors.affiliation: Institute of Plant Sciences, University of Graz, NAWI Graz, Graz, Austria.
authors.forename: Günther
authors.initials: G
authors.lastname: Zellnig
authors.affiliation: Institute of Analytical Chemistry and Food Technology, Graz University of Technology, NAWI Graz, Graz, Austria.
authors.forename: Erich
authors.initials: E
authors.lastname: Leitner
authors.affiliation: Institute of Biochemistry, Graz University of Technology, NAWI Graz, Graz, Austria.
authors.forename: Albin
authors.initials: A
authors.lastname: Hermetter
authors.affiliation: Institute of Biochemistry, Graz University of Technology, NAWI Graz, Graz, Austria.
authors.forename: Günther
authors.initials: G
authors.lastname: Daum
mesh_terms: D003566:Cytidine Diphosphate Choline / Q000378:metabolism; D005454:Fluorescence Polarization; D005656:Fungal Proteins / Q000235:genetics; D007425:Intracellular Membranes / Q000378:metabolism; D008560:Membrane Fluidity; D008745:Methylation; D008854:Microscopy, Electron; D008861:Microsomes / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D009154:Mutation; D020675:Peroxisomes / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000378:metabolism*; D010743:Phospholipids / Q000302:isolation & purification / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D013261:Sterols / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D010713:Phosphatidylcholines; D010743:Phospholipids; D013261:Sterols; D003566:Cytidine Diphosphate Choline