Capote-Maínez N, Sánchez F
Departamento de Biología Molecular de Plantas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México.
Plant Physiol. 1997 Dec;115(4):1307-17. doi: 10.1104/pp.115.4.1307.
Uricase II is a purine metabolic enzyme highly induced in root nodules during the symbiosis established between legumes and bacteria of the genera Rhizobium and Bradyrhizobium. Here we describe the characterization of bean (Phaseolus vulgaris) nodule uricase II cDNA and show that uricase II is encoded by a single gene in the bean genome. This gene is also expressed in cotyledons, roots, and hypocotyls during bean seedling establishment, and an anti-uricase antibody recognizes the protein in different seedling organs. Uricase II has also been found in Leucaena leucocephala seedlings, suggesting that it participates during seedling establishment in legumes that do not transport ureides. A 50-kD polypeptide that is detected by the anti-uricase antibody is found in cotyledons during seedling development. This higher-molecular-mass form is also detected in developing roots and hypocotyls but not in nodules. In situ hybridization experiments in root seedlings showed uricase II transcripts in the metaxylem parenchyma cells and phloem fibers of the vascular system.
尿酸酶II是一种嘌呤代谢酶，在豆科植物与根瘤菌属和慢生根瘤菌属细菌建立共生关系期间，根瘤中会大量诱导产生该酶。在此，我们描述了菜豆（Phaseolus vulgaris）根瘤尿酸酶II cDNA的特性，并表明尿酸酶II由菜豆基因组中的一个单基因编码。该基因在菜豆幼苗形成过程中的子叶、根和下胚轴中也有表达，并且一种抗尿酸酶抗体能识别不同幼苗器官中的该蛋白。在银合欢幼苗中也发现了尿酸酶II，这表明它在不运输酰脲的豆科植物幼苗形成过程中发挥作用。在幼苗发育过程中，子叶中可检测到一种由抗尿酸酶抗体识别的50-kD多肽。这种分子量更高的形式在发育中的根和下胚轴中也能检测到，但在根瘤中未检测到。根幼苗的原位杂交实验表明，尿酸酶II转录本存在于维管系统的后生木质部薄壁细胞和韧皮纤维中。
