The essential nature of sphingolipids in plants as revealed by the functional identification and characterization of the Arabidopsis LCB1 subunit of serine palmitoyltransferase
The essential nature of sphingolipids in plants as revealed by the functional identification and characterization of the Arabidopsis LCB1 subunit of serine palmitoyltransferase
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DOI：
10.1105/tpc.105.040774
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发表时间：
2006-12-01
期刊：
影响因子：
11.6
通讯作者：
Cahoon, Edgar B.
中科院分区：
文献类型：
--
作者：
Chen, Ming;Han, Gongshe;Cahoon, Edgar B.
丝氨酸棕榈酰转移酶（SPT）催化鞘脂生物合成的第一步。在酵母和哺乳动物细胞中，SPT是由LCB 1和LCB 2亚基组成的异源二聚体，它们共同形成该酶的活性位点。我们表明，预测的基因拟南芥LCB 1编码一个真正的亚基的SPT，拯救鞘脂长链碱基营养缺陷型的酿酒酵母SPT突变体与拟南芥LCB 2共表达时。此外，纯合的T-DNA插入突变体在LCB 1是不可恢复的，但活力恢复与野生型在LCB 1基因的互补。此外，部分RNA干扰（RNAi）抑制在LCB 1表达伴随着一个显着的减少植物的大小，主要是由于减少细胞扩增。基于重量的鞘脂含量在RNAi抑制植物中没有显著变化，表明植物通过减少生长来补偿鞘脂合成的下调。在LCB 1 RNAi抑制植物也表现出改变叶形态和增加饱和鞘脂长链碱基的相对量。这些结果表明，植物SPT是一种异聚体酶，鞘脂是植物细胞的重要组成部分，有助于生长和发育。
Serine palmitoyltransferase (SPT) catalyzes the first step of sphingolipid biosynthesis. In yeast and mammalian cells, SPT is a heterodimer that consists of LCB1 and LCB2 subunits, which together form the active site of this enzyme. We show that the predicted gene for Arabidopsis thaliana LCB1 encodes a genuine subunit of SPT that rescues the sphingolipid long-chain base auxotrophy of Saccharomyces cerevisiae SPT mutants when coexpressed with Arabidopsis LCB2. In addition, homozygous T-DNA insertion mutants for At LCB1 were not recoverable, but viability was restored by complementation with the wild-type At LCB1 gene. Furthermore, partial RNA interference (RNAi) suppression of At LCB1 expression was accompanied by a marked reduction in plant size that resulted primarily from reduced cell expansion. Sphingolipid content on a weight basis was not changed significantly in the RNAi suppression plants, suggesting that plants compensate for the downregulation of sphingolipid synthesis by reduced growth. At LCB1 RNAi suppression plants also displayed altered leaf morphology and increases in relative amounts of saturated sphingolipid long-chain bases. These results demonstrate that plant SPT is a heteromeric enzyme and that sphingolipids are essential components of plant cells and contribute to growth and development.