title: Yeast cells accumulate excess endogenous palmitate in phosphatidylcholine by acyl chain remodeling involving the phospholipase B Plb1p.
abstract: In the yeast Saccharomyces cerevisiae, the molecular species profile of the major membrane glycerophospholipid phosphatidylcholine (PC) is determined by the molecular species-selectivity of the biosynthesis routes and by acyl chain remodeling. Overexpression of the glycerol-3-phosphate acyltransferase Sct1p was recently shown to induce a strong increase in the cellular content of palmitate (C16:0). Using stable isotope labeling and mass spectrometry, the present study shows that wild type yeast overexpressing Sct1p incorporates excess C16:0 into PC via the methylation of PE, the CDP-choline route, and post-synthetic acyl chain remodeling. Overexpression of Sct1p increased the extent of remodeling of PE-derived PC, providing a novel tool to perform mechanistic studies on PC acyl chain exchange. The exchange of acyl chains occurred at both the sn-1 and sn-2 positions of the glycerol backbone of PC, and required the phospholipase B Plb1p for optimal efficiency. Sct1p-catalyzed acyl chain exchange, the acyl-CoA binding protein Acb1p, the Plb1p homologue Plb2p, and the glycerophospholipid:triacylglycerol transacylase Lro1p were not required for PC remodeling. The results indicate that PC serves as a buffer for excess cellular C16:0.
authors.affiliation: Utrecht University, Utrecht, The Netherlands.
authors.forename: Cedric H
authors.initials: CH
authors.lastname: De Smet
authors.forename: Ruud
authors.initials: R
authors.lastname: Cox
authors.forename: Jos F
authors.initials: JF
authors.lastname: Brouwers
authors.forename: Anton I P M
authors.initials: AI
authors.lastname: de Kroon
mesh_terms: D002352:Carrier Proteins / Q000378:metabolism*; D005992:Glycerol-3-Phosphate O-Acyltransferase / Q000378:metabolism*; D008245:Lysophospholipase / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D010168:Palmitates / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000378:metabolism*; D010714:Phosphatidylethanolamines / Q000378:metabolism*; D054467:Phospholipases A2 / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: C492820:ACB1 protein, S cerevisiae; D002352:Carrier Proteins; D008565:Membrane Proteins; D010168:Palmitates; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D029701:Saccharomyces cerevisiae Proteins; D005992:Glycerol-3-Phosphate O-Acyltransferase; D054467:Phospholipases A2; D008245:Lysophospholipase; C490270:PLB1 protein, S cerevisiae