The inositol oxygenase gene family of Arabidopsis is involved in the biosynthesis of nucleotide sugar precursors for cell-wall matrix polysaccharides
The inositol oxygenase gene family of Arabidopsis is involved in the biosynthesis of nucleotide sugar precursors for cell-wall matrix polysaccharides
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DOI：
10.1007/s00425-004-1441-0
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发表时间：
2005-05-01
期刊：
影响因子：
4.3
通讯作者：
Tenhaken, R
中科院分区：
文献类型：
--
作者：
Kanter, U;Usadel, B;Tenhaken, R
核苷酸糖UDP-葡萄糖醛酸（UDP-GlcA）是植物细胞壁聚合物的半乳糖醛酸、木糖、芹菜糖和阿拉伯糖残基的主要前体。UDP-GlcA可以通过拟南芥中的两种不同功能途径合成，涉及UDP-葡萄糖脱氢酶或肌醇加氧酶作为初始酶反应，将碳水化合物引导到用于细胞壁生物合成的UDP糖库中。在拟南芥中分析了酶肌醇加氧酶（MIOX）的基因。它们代表了一个包含四个成员的小基因家族。所有这些成员的转录指示瞬时和器官特异性的基因表达模式，在生长的植物组织中通过RT-PCR和启动子：：GUS报告基因系分析。两种同种型（MIOX 1、MIOX 2）在植物的几乎所有组织中表达，而MIOX 4和MIOX 5的表达主要限于花，特别是成熟的花粉。分离MIOX基因中的T-DNA插入系;然而，单敲除显示出与野生型相似的生长表型。与野生型植物相比，这些突变体中细胞壁的单糖组成没有显著变化。然而，H-3-肌醇掺入到幼苗的壁聚合物中在突变株系Delta MIOX 1和Delta MIOX 2中受到极大损害，这是在幼苗中表达的唯一同种型。
The nucleotide sugar UDP-glucuronic acid (UDP-GlcA) is the principal precursor for galacturonic acid, xylose, apiose and arabinose residues of the plant cell-wall polymers. UDP-GlcA can be synthesized by two different functional pathways in Arabidopsis involving either UDP-glucose dehydrogenase or inositol oxygenase as the initial enzyme reaction to channel carbohydrates into a pool of UDP sugars used for cell-wall biosynthesis. The genes for the enzyme myo-inositol oxygenase (MIOX) were analyzed in Arabidopsis. They represent a small gene family containing four members. The transcription of all those members indicates a transient and organ-specific gene expression pattern in growing plant tissues as analyzed by RT-PCR and in promoter::GUS reporter gene lines. Two isoforms (MIOX1, MIOX2) are expressed in almost all tissues of the plant, whereas the expression of MIOX4 and MIOX5 is largely restricted to flowers, particularly maturing pollen. T-DNA insertion lines in MIOX genes were isolated; however, single knock-outs show growth phenotypes similar to the wild type. The monosaccharide composition of the cell wall in these mutants is not significantly changed compared to wild type plants. However, the incorporation of H-3-inositol into wall polymers of seedlings is greatly impaired in the mutant lines Delta MIOX1 and Delta MIOX2, which are the only isoforms that are expressed in seedlings.