Lysophosphatidylcholine metabolism in Saccharomyces cerevisiae: the role of P-type ATPases in transport and a broad specificity acyltransferase in acylation.
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.
Riekhof
Wayne R
WR
Department of Medicine, Program in Cell Biology, National Jewish Medical and Research Center, Denver, Colorado 80206, USA.
Wu
James
J
Gijón
Miguel A
MA
Zarini
Simona
S
Murphy
Robert C
RC
Voelker
Dennis R
DR
D008243:1-Acylglycerophosphocholine O-Acyltransferase / Q000235:genetics / Q000378:metabolism*; D018528:ATP-Binding Cassette Transporters; D000215:Acylation; D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D001693:Biological Transport, Active / Q000502:physiology; D002462:Cell Membrane / Q000201:enzymology* / Q000235:genetics; D017353:Gene Deletion; D008244:Lysophosphatidylcholines / Q000096:biosynthesis* / Q000235:genetics; D008246:Lysophospholipids / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D050918:Phosphatidylethanolamine N-Methyltransferase / Q000235:genetics / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity / Q000502:physiology
D018528:ATP-Binding Cassette Transporters; C478771:Lem3 protein, S cerevisiae; D008244:Lysophosphatidylcholines; D008246:Lysophospholipids; D026901:Membrane Transport Proteins; D010714:Phosphatidylethanolamines; D029701:Saccharomyces cerevisiae Proteins; C008301:lysophosphatidylethanolamine; C483858:phosphatidylethanolamine; C494486:CHO2 protein, S cerevisiae; D050918:Phosphatidylethanolamine N-Methyltransferase; D008243:1-Acylglycerophosphocholine O-Acyltransferase; D000251:Adenosine Triphosphatases; C480602:Dnf2 protein, S cerevisiae; C480601:Dnf1 protein, S cerevisiae