The Arabidopsis thaliana Myo-Inositol 1-Phosphate Synthase1 Gene Is Required for Myo-inositol Synthesis and Suppression of Cell Death
The Arabidopsis thaliana Myo-Inositol 1-Phosphate Synthase1 Gene Is Required for Myo-inositol Synthesis and Suppression of Cell Death
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DOI：
10.1105/tpc.109.071779
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发表时间：
2010-03-01
期刊：
影响因子：
11.6
通讯作者：
Gillaspy, Glenda E.
中科院分区：
文献类型：
--
作者：
Donahue, Janet L.;Alford, Shannon R.;Gillaspy, Glenda E.
L-肌醇1-磷酸合酶（MIPS; EC 5.5.1.4）催化肌醇合成中的限速步骤，肌醇是细胞中的关键化合物。植物含有多个MIPS基因，它们编码高度相似的酶。我们对拟南芥中三个MIPS基因的表达模式进行了研究，发现MIPS 1在大多数细胞类型和发育阶段都有表达，而MIPS 2和MIPS 3主要局限于维管或相关组织。MIPS 1，而不是MIPS 2或MIPS 3，是种子发育所必需的，是对盐和脱落酸的生理反应所必需的，也是抑制细胞死亡所必需的。具体而言，MIPS 1的损失导致具有卷曲叶片和自发产生病变的较小植物。mips 1突变体具有较低的肌醇，抗坏血酸和磷脂酰肌醇水平，而基础水平的肌醇（1，4，5）P-3在mips 1突变体中没有改变。此外，mips 1突变体表现出神经酰胺，鞘脂前体与细胞死亡的水平升高，并补充了MIPS 1-绿色荧光蛋白（GFP）融合构建体。MIPS 1-、MIPS 2-和MIPS 3-GFP各自定位于细胞质。因此，MIPS 1对肌醇水平具有显著影响，肌醇水平对于维持调节生长、发育和细胞死亡的抗坏血酸、磷脂酰肌醇和神经酰胺的水平至关重要。
L-myo-inositol 1-phosphate synthase (MIPS; EC 5.5.1.4) catalyzes the rate-limiting step in the synthesis of myo-inositol, a critical compound in the cell. Plants contain multiple MIPS genes, which encode highly similar enzymes. We characterized the expression patterns of the three MIPS genes in Arabidopsis thaliana and found that MIPS1 is expressed in most cell types and developmental stages, while MIPS2 and MIPS3 are mainly restricted to vascular or related tissues. MIPS1, but not MIPS2 or MIPS3, is required for seed development, for physiological responses to salt and abscisic acid, and to suppress cell death. Specifically, a loss in MIPS1 resulted in smaller plants with curly leaves and spontaneous production of lesions. The mips1 mutants have lower myo-inositol, ascorbic acid, and phosphatidylinositol levels, while basal levels of inositol (1,4,5)P-3 are not altered in mips1 mutants. Furthermore, mips1 mutants exhibited elevated levels of ceramides, sphingolipid precursors associated with cell death, and were complemented by a MIPS1-green fluorescent protein (GFP) fusion construct. MIPS1-, MIPS2-, and MIPS3-GFP each localized to the cytoplasm. Thus, MIPS1 has a significant impact on myo-inositol levels that is critical for maintaining levels of ascorbic acid, phosphatidylinositol, and ceramides that regulate growth, development, and cell death.