Yeast cells accumulate excess endogenous palmitate in phosphatidylcholine by acyl chain remodeling involving the phospholipase B Plb1p.

Cedric H De Smet, Ruud Cox, Jos F Brouwers, Anton I P M de Kroon

Utrecht University, Utrecht, The Netherlands.

Biochimica et biophysica acta 2013 Jun

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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. Copyright © 2013 Elsevier B.V. All rights reserved.

Citation

Cedric H De Smet, Ruud Cox, Jos F Brouwers, Anton I P M de Kroon. Yeast cells accumulate excess endogenous palmitate in phosphatidylcholine by acyl chain remodeling involving the phospholipase B Plb1p. Biochimica et biophysica acta. 2013 Jun;1831(6):1167-76