A PHOSPHATIDYLINOSITOL 3-KINASE IS INDUCED DURING SOYBEAN NODULE ORGANOGENESIS AND IS ASSOCIATED WITH MEMBRANE PROLIFERATION
A PHOSPHATIDYLINOSITOL 3-KINASE IS INDUCED DURING SOYBEAN NODULE ORGANOGENESIS AND IS ASSOCIATED WITH MEMBRANE PROLIFERATION
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DOI：
10.1073/pnas.91.20.9617
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发表时间：
1994-09-27
影响因子：
11.1
通讯作者：
VERMA, DPS
中科院分区：
文献类型：
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作者：
HONG, ZG;VERMA, DPS
磷脂酰肌醇3-激酶（PI3K）是哺乳动物细胞中多种受体酪氨酸激酶复合物的重要组成部分，也是酵母细胞分裂和液泡蛋白分选所需的关键酶。据我们所知，这种酶还没有在植物中被鉴定出来。我们报道了大豆PI3K cdna的克隆和表征，并提供了诱导这种特殊形式的酶特异于结节器官发生的证据。根型PI3K的表达在根瘤器官发生过程中受到抑制，在成熟根瘤中被重新诱导。引物扩展结果表明，PI3K的结节形式编码基因在幼龄（12-15 d）根瘤中与膜增殖平行高表达，但在成熟根瘤中被抑制。PI3K cDNA的根型（SPI3K-5）编码一个814个氨基酸的肽，结节型（SPI3K-1）编码一个812个氨基酸的肽。两种cdna在编码区98%的序列相同，但在非编码区不同。大豆PI3K cdna编码的多肽与哺乳动物和酵母细胞中的PI3K激酶和磷脂酰肌醇4激酶具有显著的序列同源性（相似性为50-60%，同源性为20-40%）。大肠杆菌在肌醇环的D-3位置特异性表达大豆PI3K磷酸化的磷脂酰肌醇，生成3-磷酸磷脂酰肌醇。在年轻结节的膜增殖过程中，特异性PI3K活性的时间增加表明PI3K在形成亚细胞室的类细菌周围膜的发育中起关键作用。
Phosphatidylinositol 3-kinase (PI3K) is an important component of various receptor tyrosine kinase complexes in mammalian cells and a key enzyme required for cell division and vacuolar protein sorting in yeast. To our knowledge, this enzyme has not been characterized in plants. We report the cloning and characterization of soybean PI3K cDNAs and present evidence for the induction of a distinctive form of this enzyme specific to nodule organogenesis. Expression of the root form of PI3K is repressed during nodule organogenesis and is reinduced in mature nodules. Primer extension results showed that the gene encoding the nodule form of PI3K is highly expressed in young (12-15 day old) root nodules in parallel with membrane proliferation but is re pressed in mature nodules. The root form of the PI3K cDNA (SPI3K-5) encodes a peptide of 814 amino acids and the nodule form (SPI3K-1) encodes a peptide of 812 amino acids. Both cDNAs share 98% sequence identity in the coding region but differ in the noncoding regions. The polypeptides encoded by soybean PI3K cDNAs Show significant sequence homology (50-60% similarity and 20-40% identity) to both PI3Ks and phosphatidylinositol 4-kinases from mammalian and yeast cells. Escherichia coli expressed soybean PI3K phosphorylated phosphatidylinositol specifically at the D-3 position of the inositol ring to generate phosphatidylinositol 3-phosphate. The temporal increase of a specific PI3K activity during membrane proliferation in young nodules suggests that PI3K plays a pivotal role in development of the peribacteroid membrane forming a subcellular compartment.