A genetic screen for aminophospholipid transport mutants identifies the phosphatidylinositol 4-kinase, Stt4p, as an essential component in phosphatidylserine metabolism
A genetic screen for aminophospholipid transport mutants identifies the phosphatidylinositol 4-kinase, Stt4p, as an essential component in phosphatidylserine metabolism
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DOI：
10.1074/jbc.273.21.13189
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发表时间：
1998-05-22
影响因子：
4.8
通讯作者：
Voelker, DR
中科院分区：
文献类型：
--
作者：
Trotter, PJ;Wu, WI;Voelker, DR
为了了解细胞内脂质转运的分子机制，我们重点研究了酿酒酵母中从头合成氨基磷脂所需的特定事件。已经开发出一种遗传系统，用于检查内质网中磷脂酰丝氨酸 (PtdSer) 的合成及其转运至高尔基体/液泡中的 PtdSer 脱羧酶 2 并由 PtdSer 脱羧酶 2 脱羧之间的步骤。我们分离出一个突变体，表示为 pstB1，尽管 PtdSer 脱羧酶 2 活性正常，但它会积累 PtdSer 并减少磷脂酰乙醇胺的形成。 PtdSer 代谢的损伤与细胞器间脂质转运的缺陷一致。分离出与突变互补的基因组 DNA 克隆，测序显示该克隆含有 STT4 基因，编码磷脂酰肌醇 4-激酶。 pstB1突变体表现出Stt4p型磷脂酰肌醇Li激酶活性缺陷，直接基因替换表明STT4是突变体中的缺陷基因。 STT4 无效等位基因 (stt4 Delta::HIS3) 的创建证明该基因是必需的。这些结果提供了证据表明磷酸肌醇参与细胞内氨基磷脂转运的调节。
In an effort to understand molecular mechanisms of intracellular lipid transport, we have focused upon specific events required for de novo aminophospholipid synthesis in the yeast Saccharomyces cerevisiae. A genetic system for examining the steps between phosphatidylserine (PtdSer) synthesis in the endoplasmic reticulum and its transport to and decarboxylation by PtdSer decarboxylase 2 in the Golgi/vacuole has been developed. We have isolated a mutant, denoted pstB1, that accumulates PtdSer and has diminished phosphatidylethanolamine formation despite normal PtdSer decarboxylase 2 activity. The lesion in PtdSer metabolism is consistent with a defect in interorganelle lipid transport. A genomic DNA clone that complements the mutation was isolated, and sequencing revealed that the clone contains the STT4 gene, encoding a phosphatidylinositol 4-kinase. The pstB1 mutant exhibits a defect in Stt4p-type phosphatidylinositol Li-kinase activity, and direct gene replacement indicates that STT4 is the defective gene in the mutant. Creation of an STT4 null allele (stt4 Delta::HIS3) demonstrates the gene is essential. These results provide evidence that implicates phosphoinositides in the regulation of intracellular aminophospholipid transport.