MOE Key Laboratory of Bioinformatics, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, People's Republic of China.
Plant Cell Rep. 2014 Jan;33(1):25-33. doi: 10.1007/s00299-013-1509-z. Epub 2013 Oct 8.
Genetic and molecular analysis of an Arabidopsis root development mutant identified a putative dehydrogenase gene involved in homoserine biosynthesis. In higher plants, homoserine (Hse) is derived from aspartate (Asp) and is an important intermediate for production of methionine (Met), threonine (Thr), and isoleucine (Ile). In Arabidopsis, six enzymes involved in the biosynthesis of Hse from Asp have been well characterized. It is not known, however, whether there exist other enzymes involved in this process. In this work, we characterized an Arabidopsis mutant, ara (altered root architecture), with a short primary root and an increased number of lateral roots. Genetic and molecular analysis indicated that the ARA gene encodes a protein with a D-isomer specific 2-hydroxyacid dehydrogenase domain. ARA is expressed in all plant organs and is localized in the cell periphery. The ara mutant phenotypes can be rescued by exogenously applied Hse, Met, Ile and 2-oxobutanoate. Based on the results presented here, we propose that the ARA protein may be a dehydrogenase involved in homoserine biosynthesis.
拟南芥根发育突变体的遗传和分子分析鉴定出一个参与高丝氨酸生物合成的假定脱氢酶基因。在高等植物中，高丝氨酸（Hse）来源于天冬氨酸（Asp），是甲硫氨酸（Met）、苏氨酸（Thr）和异亮氨酸（Ile）生产的重要中间体。在拟南芥中，已有 6 种参与 Asp 生成 Hse 的酶得到了很好的描述。然而，尚不清楚是否存在其他参与该过程的酶。在这项工作中，我们对一个具有短主根和增加的侧根的拟南芥突变体 ara（改变的根结构）进行了表征。遗传和分子分析表明，ARA 基因编码一种具有 D-异构体特异性 2-羟基酸脱氢酶结构域的蛋白质。ARA 在所有植物器官中表达，并定位于细胞外周。ara 突变体表型可通过外源施加 Hse、Met、Ile 和 2-氧代丁酸得到挽救。根据这里提出的结果，我们提出 ARA 蛋白可能是参与高丝氨酸生物合成的脱氢酶。
