Lysophosphatidylcholine metabolism in Saccharomyces cerevisiae: the role of P-type ATPases in transport and a broad specificity acyltransferase in acylation

J Biol Chem. 2007 Dec 21;282(51):36853-61. doi: 10.1074/jbc.M706718200. Epub 2007 Oct 21.

Abstract

We recently described a new route for the synthesis of phosphatidylethanolamine (PtdEtn) from exogenous lyso-PtdEtn, which we have termed the exogenous lysolipid metabolism (ELM) pathway. The ELM pathway for lyso-PtdEtn requires the action of plasma membrane P-type ATPases Dnf1p and Dnf2p and their requisite beta-subunit, Lem3p, for the active uptake of lyso-PtdEtn. In addition, the acyl-CoA-dependent acyltransferase, Ale1p, mediates the acylation of the imported lysolipid to form PtdEtn. We now report that these components of the lyso-PtdEtn ELM pathway are also active with lyso-1-acyl-2-hydroxyl-sn-glycero-3-phosphocholine (PtdCho) as a substrate. Lyso-PtdCho supports the growth of a choline auxotrophic pem1Delta pem2Delta strain. Uptake of radiolabeled lyso-PtdCho was impaired by the dnf2Delta and lem3Delta mutations. Introduction of a lem3Delta mutation into a pem1Delta pem2Delta background impaired the ability of the resulting strain to grow with lyso-PtdCho as the sole precursor of PtdCho. After import of lyso-PtdCho, the recently characterized lyso-PtdEtn acyltransferase, Ale1p, functioned as the sole lyso-PtdCho acyltransferase in yeast. A pem1Delta pem2Delta ale1Delta strain grew with lyso-PtdCho as a substrate but showed a profound reduction in PtdCho content when lyso-PtdCho was the only precursor of PtdCho. Ale1p acylates lyso-PtdCho with a preference for monounsaturated acyl-CoA species, and the specific LPCAT activity of Ale1p in yeast membranes is >50-fold higher than the basal rate of de novo aminoglycerophospholipid biosynthesis from phosphatidylserine synthase activity. In addition to lyso-PtdCho, lyso-PtdEtn, and lyso-phosphatidic acid, Ale1p was also active with lysophosphatidylserine, lysophosphatidylglycerol, and lysophosphatidylinositol as substrates. These results establish a new pathway for the net synthesis of PtdCho in yeast and provide new tools for the study of PtdCho synthesis, transport, and remodeling.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 1-Acylglycerophosphocholine O-Acyltransferase / genetics
  • 1-Acylglycerophosphocholine O-Acyltransferase / metabolism*
  • ATP-Binding Cassette Transporters
  • Acylation
  • Adenosine Triphosphatases / genetics
  • Adenosine Triphosphatases / metabolism*
  • Biological Transport, Active / physiology
  • Cell Membrane / enzymology*
  • Cell Membrane / genetics
  • Gene Deletion
  • Lysophosphatidylcholines / biosynthesis*
  • Lysophosphatidylcholines / genetics
  • Lysophospholipids / metabolism
  • Membrane Transport Proteins / genetics
  • Membrane Transport Proteins / metabolism
  • Phosphatidylethanolamine N-Methyltransferase / genetics
  • Phosphatidylethanolamine N-Methyltransferase / metabolism
  • Phosphatidylethanolamines / metabolism
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Substrate Specificity / physiology

Substances

  • ATP-Binding Cassette Transporters
  • Lem3 protein, S cerevisiae
  • Lysophosphatidylcholines
  • Lysophospholipids
  • Membrane Transport Proteins
  • Phosphatidylethanolamines
  • Saccharomyces cerevisiae Proteins
  • lysophosphatidylethanolamine
  • phosphatidylethanolamine
  • CHO2 protein, S cerevisiae
  • Phosphatidylethanolamine N-Methyltransferase
  • 1-Acylglycerophosphocholine O-Acyltransferase
  • Adenosine Triphosphatases
  • Dnf2 protein, S cerevisiae
  • Dnf1 protein, S cerevisiae