Biosynthesis of phosphatidic acid in lipid particles and endoplasmic reticulum of Saccharomyces cerevisiae
Biosynthesis of phosphatidic acid in lipid particles and endoplasmic reticulum of Saccharomyces cerevisiae
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DOI：
10.1128/jb.179.24.7611-7616.1997
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发表时间：
1997-12-01
影响因子：
3.2
通讯作者：
Daum, G
中科院分区：
文献类型：
--
作者：
Athenstaedt, K;Daum, G
酵母酿酒酵母的脂质颗粒含有两种酶，其逐步将甘油-3-磷酸酰化为磷脂酸，磷脂酸是脂质生物合成中的关键中间体。在slc 1破坏物YMN 5（M. M. Nagiec et al.J.Biol.Chem.268：22156-22163，1993）酰化在第一步后停止，导致溶血磷脂酸的积累。二维凝胶电泳证实Slc 1 p是脂质颗粒的组分。S. Tillman和R. M. Bell，J.Biol.Chem.261：9144-9149，1986）在体外基本上没有甘油-3-磷酸酰基转移酶活性，磷脂酸的合成通过将来自YMN 5和TTA 1的脂质颗粒组合来重构。这些结果表明，两种不同的酶是必需的磷脂酸合成的脂质颗粒：第一步，甘油-3-磷酸的酰化，是由一个假定的Gat 1 p催化;第二步，溶血磷脂酸的酰化，需要Slc 1 p。令人惊讶的是，YMN 5和TTA 1突变体像相应的野生型一样生长，因为这两种突变体的内质网具有形成减少但显著量的磷脂酸的能力。因此，slc 1 gat 1双突变体也是可行的。来自该双突变体的脂质颗粒不能完全酰化甘油-3-磷酸，而内质网膜具有合成磷脂酸的残余酶活性。因此，酵母含有至少两个独立的磷脂酸生物合成系统。
Lipid particles of the yeast Saccharomyces cerevisiae harbor two enzymes that stepwise acylate glycerol-3-phosphate to phosphatidic acid, a key intermediate in lipid biosynthesis. In lipid particles of the slc1 disruptant YMN5 (M. M. Nagiec et al. J. Biol. Chem. 268:22156-22163, 1993) acylation stops after the first step, resulting in the accumulation of lysophosphatidic acid, Two-dimensional gel electrophoresis confirmed that Slc1p is a component of lipid particles, Lipid particles of a second mutant strain,TTA1 (T. S. Tillman and R. M. Bell, J. Biol. Chem. 261:9144-9149, 1986), which harbors a point mutation in the GAT gene, are essentially devoid of glycerol-3-phosphate acyltransferase activity in vitro., Synthesis of phosphatidic acid is reconstituted by combining lipid particles from YMN5 and TTA1. These results indicate that two distinct enzymes are necessary for phosphatidic acid synthesis in lipid particles: the first step, acylation of glycerol-3-phosphate, is catalyzed by a putative Gat1p; the second step, acylation of lysophosphatidic acid, requires Slc1p. Surprisingly, YMN5 and TTA1 mutants grow like the corresponding wild types because the endoplasmic reticulum of both mutants has the capacity to form a reduced but significant amount of phosphatidic acid. As a consequence, an slc1 gat1 double mutant is also viable, Lipid particles from this double mutant fail completely to acylate glycerol-3-phosphate, whereas endoplasmic reticulum membranes harbor residual enzyme activities to synthesize phosphatidic acid, Thus, yeast contains at least two independent systems of phosphatidic acid biosynthesis.