Unnasch T R, Bradley J, Beauchamp J, Tuan R, Kennedy M W
University of Alabama at Birmingham, Division of Geographic Medicine, 35294-2170, USA.
Mol Biochem Parasitol. 1999 Nov 30;104(2):259-69. doi: 10.1016/s0166-6851(99)00152-8.
Steroids and retinoids are important regulators of development in invertebrates and vertebrates. The central mediators of action of these compounds are their cognate receptors, which together form a family of proteins known as the nuclear receptor family. Previous studies have demonstrated that the genome of Onchocerca volvulus encodes at least three members of the nuclear receptor family. Here, the characterization of one member of this family from O. volvulus, designated OvNR-2, is described. OvNR-2 was found to be most similar to a number of vertebrate retinoic acid receptors and to the Drosophila melanogaster EiP78c protein. Modeling studies suggest that OvNR-2 forms a boot shaped ligand-binding cavity of a shape and size that can bind steroids. Expression of the mRNA corresponding to OvNR-2 is tightly regulated in adult parasites, appearing only in the extended intrauterine microfilariae. The protein derived from expression of the OvNR-2 cDNA in a bacterial system is recognized by serum antibodies in a majority of individuals infected with O. volvulus.
类固醇和类视黄醇是无脊椎动物和脊椎动物发育的重要调节因子。这些化合物作用的核心介质是它们的同源受体，这些受体共同构成了一个被称为核受体家族的蛋白质家族。先前的研究表明，旋盘尾丝虫的基因组编码核受体家族的至少三个成员。在此，描述了来自旋盘尾丝虫的该家族一个成员的特征，命名为OvNR - 2。发现OvNR - 2与许多脊椎动物视黄酸受体以及果蝇EiP78c蛋白最为相似。模型研究表明，OvNR - 2形成了一个靴子形状的配体结合腔，其形状和大小能够结合类固醇。与OvNR - 2相对应的mRNA在成年寄生虫中受到严格调控，仅出现在延长的子宫内微丝蚴中。在细菌系统中由OvNR - 2 cDNA表达产生的蛋白质能被大多数感染旋盘尾丝虫的个体的血清抗体识别。
