title: Incorporation and remodeling of extracellular phosphatidylcholine with short acyl residues in Saccharomyces cerevisiae.
abstract: The pem1/cho2 pem2/opi3 double mutant of Saccharomyces cerevisiae, which is auxotrophic for choline because of the deficiency in methylation activities of phosphatidylethanolamine, grew in the presence of 0.1 mM dioctanoyl-phosphatidylcholine (diC(8)PC). Analysis of the metabolism of methyl-(13)C-labeled diC(8)PC ((methyl-(13)C)(3)-diC(8)PC) by electrospray ionization tandem mass spectrometry (ESI-MS/MS) revealed that it was rapidly converted to (methyl-(13)C)(3)-PCs containing C16 or C18 acyl chains. (Methyl-(13)C)(3)-8:0-lyso-PC, (methyl-(13)C)(3)-8:0-16:0-PC and (methyl-(13)C)(3)-8:0-16:1-PC, which are the probable intermediate molecular species of acyl chain remodeling, appeared immediately after 5 min of pulse-labeling and decreased during the subsequent chase period. These results indicate that diC(8)PC was taken up by the pem1 pem2 double mutant and that the acyl chains of diC(8)PC were exchanged with longer yeast fatty acids. The temporary appearance of (methyl-(13)C)(3)-8:0-lyso-PC suggests that the remodeling reaction may consist of deacylation and reacylation by phospholipase activities and acyltransferase activities, respectively. The detailed analyses of the structures of (methyl-(13)C)(3)-8:0-16:0-PC and (methyl-(13)C)(3)-8:0-16:1-PC by MS/MS and MS(3) strongly suggest that most (methyl-(13)C)(3)-8:0-16:0-PCs have a C16:0 acyl chain at sn-1 position, whereas (methyl-(13)C)(3)-8:0-16:1-PCs have a C16:1 acyl chain at either sn-1 or sn-2 position in a similar frequency, implying that the initial C16:0 acyl chain substitution prefers the sn-1 position; however, the C16:1 acyl chain substitution starts at both sn-1 and sn-2 positions. The current study provides a pivotal insight into the acyl chain remodeling of phospholipids in yeast.
authors.affiliation: Department of Biotechnology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Tanaka
authors.forename: Ryouichi
authors.initials: R
authors.lastname: Fukuda
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Ono
authors.forename: Hiroki
authors.initials: H
authors.lastname: Eguchi
authors.forename: Shinya
authors.initials: S
authors.lastname: Nagasawa
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nakatani
authors.forename: Hidenori
authors.initials: H
authors.lastname: Watanabe
authors.forename: Hiroki
authors.initials: H
authors.lastname: Nakanishi
authors.forename: Ryo
authors.initials: R
authors.lastname: Taguchi
authors.forename: Akinori
authors.initials: A
authors.lastname: Ohta
mesh_terms: D000215:Acylation; D000217:Acyltransferases / Q000378:metabolism; D003470:Culture Media; D005110:Extracellular Space / Q000378:metabolism*; D017353:Gene Deletion; D005800:Genes, Fungal; D007553:Isotope Labeling; D008245:Lysophospholipase / Q000378:metabolism; D010713:Phosphatidylcholines / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D012995:Solubility; D014867:Water
chemical_list: C111346:1,2-dioctanoyl-sn-glycero-3-phosphocholine; D003470:Culture Media; D010713:Phosphatidylcholines; D014867:Water; D000217:Acyltransferases; D008245:Lysophospholipase