Two distinct uricase II (nodulin 35) genes are differentially expressed in soybean plants.
Two distinct uricase II (nodulin 35) genes are differentially expressed in soybean plants.
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两个不同的尿酸酶 II（结节蛋白 35）基因在大豆植物中差异表达。
DOI：
10.1094/mpmi.1997.10.6.735
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发表时间：
1997
影响因子：
3.5
通讯作者：
H. Kouchi
中科院分区：
文献类型：
--
作者：
K. Takane;S. Tajima;H. Kouchi
根瘤特异性尿酸酶（尿酸酶II）是一个同源四聚体的33-kDa的多肽，甜蛋白35，并在同化氮的微共生体固定在大多数豆科植物中，有确定的结节起着关键作用。我们已经从大豆基因组文库中分离出两个不同的基因，UR 2和UR 9，它们编码大豆球蛋白35。从根瘤cDNA文库中也分离出了它们相应的cDNA。UR 2和UR 9都编码309个氨基酸的蛋白质，具有12个氨基酸的差异。利用反转录-聚合酶链反应技术，对这两个基因在大豆不同器官中的表达进行了检测。UR 9的表达几乎是特异性的根瘤，虽然它表达在根，初生叶，和发展中的种子在非常低的水平。与此相反，UR 2转录本存在于几乎所有的植物器官中，在低水平，但没有增强的表达在结节中观察到。因此，UR 9表现为一个尿酸酶基因，而UR 2是一个非共生尿酸酶II基因。其潜在启动子区域的序列在翻译起始位点上游约400 bp的区域内具有高度同源性。这些结果表明，共生和非共生尿酸酶II基因分歧的基因复制和启动子序列中相对较小的改变，使结节特异性表达。
Nodule-specific uricase (uricase II) is a homotetramer of a 33-kDa polypeptide, nodulin 35, and plays a key role in the assimilation of nitrogen fixed by microsymbionts in most legumes that have determinate nodules. We have isolated two distinct genes, UR2 and UR9, that encode for nodulin 35 from a soybean genomic library. Their corresponding cDNAs were also isolated from a nodule cDNA library. UR2 and UR9 both encode for 309 amino acid proteins with 12 amino acid differences. The expression of these two genes in various organs of soybean was examined by reverse transcription-polymerase chain reaction with primers specific to each cDNA sequences. Expression of UR9 was almost specific in root nodules, although it was expressed in roots, primary leaves, and developing seed at very low levels. In contrast, the UR2 transcripts were present in almost all plant organs at low levels, but no enhancement of the expression was observed in nodules. Thus, UR9 behaves as a nodulin gene, whereas UR2 is a nonsymbiotic uricase II gene. The sequences of their potential promoter regions share high homology within regions up to about 400 bp upstream from the translation initiation sites. These results suggest that symbiotic and nonsymbiotic uricase II genes diverged by gene duplication and that relatively small alterations in the promoter sequence enable the nodule-specific expression.