Ferreira Thierry, Régnacq Matthieu, Alimardani Parissa, Moreau-Vauzelle Carole, Bergès Thierry
Laboratoire de Génétique de la Levure, CNRS-UMR6161, Université de Poitiers, 40 avenue du Recteur Pineau, 86022 Poitiers CEDEX, France.
Biochem J. 2004 Mar 15;378(Pt 3):899-908. doi: 10.1042/BJ20031064.
In the yeast Saccharomyces cerevisiae, UFA (unsaturated fatty acids) and ergosterol syntheses are aerobic processes that require haem. We took advantage of a strain affected in haem synthesis ( hem1 Delta) to starve specifically for one or the other of these essential lipids in order to examine the consequences on the overall lipid composition. Our results demonstrate that reserve lipids (i.e. triacylglycerols and steryl esters) are depleted independently of haem availability and that their UFA and sterol content is not crucial to sustain residual growth under lipid depletion. In parallel to UFA starvation, a net accumulation of SFA (saturated fatty acids) is observed as a consequence of haem biosynthesis preclusion. Interestingly, the excess SFA are not mainly stored within triacylglycerols and steryl esters but rather within specific phospholipid species, with a marked preference for PtdIns. This results in an increase in the cellular PtdIns content. However, neutral lipid homoeostasis is perturbed under haem starvation. The contribution of two lipid particle-associated proteins (namely Tgl1p and Dga1p) to this process is described.
在酿酒酵母中，不饱和脂肪酸（UFA）和麦角固醇的合成是需要血红素的需氧过程。我们利用一株血红素合成受影响的菌株（hem1Δ），分别特异性地使这两种必需脂质之一缺乏，以研究其对整体脂质组成的影响。我们的结果表明，储备脂质（即三酰甘油和甾醇酯）的消耗与血红素的可利用性无关，并且它们的UFA和甾醇含量对于在脂质缺乏条件下维持残余生长并非至关重要。与UFA缺乏同时，由于血红素生物合成受阻，观察到饱和脂肪酸（SFA）的净积累。有趣的是，过量的SFA并非主要储存在三酰甘油和甾醇酯中，而是储存在特定的磷脂种类中，尤其偏好磷脂酰肌醇（PtdIns）。这导致细胞中PtdIns含量增加。然而，在血红素饥饿条件下，中性脂质稳态受到干扰。描述了两种与脂质颗粒相关的蛋白质（即Tgl1p和Dga1p）在这一过程中的作用。
