DROSOPHILA PATTERNS FOR TWO PTERIN COFACTOR DEFECTS

蝶呤辅因子四氢生物蝶呤（H4 B）和异蝶呤（MoCo）的生物合成中的先天错误与严重的人类疾病相关。H4 B合成中的遗传变异与严重的人类疾病有关。H4 B合成中的遗传变异与诸如非典型苯丙酮尿症、帕金森病和肌张力障碍等疾病相关。H4 B对这些过程的重要性在于其作为苯丙氨酸、酪氨酸和色氨酸羟化酶的必需辅因子的作用，所述酶参与氨基酸降解和儿茶酚胺和5-羟色胺的生物合成。MoCo作为钼羟化酶如亚硫酸盐氧化酶和黄嘌呤脱氢酶的必需酶辅因子发挥作用。MoCo生物合成的遗传缺陷与严重衰弱性神经障碍、钼辅因子缺乏和黄嘌呤尿症（嘌呤代谢疾病）相关。所提出的研究利用黑腹果蝇作为蝶呤辅因子生物合成的遗传模型系统，黑腹果蝇是蝶呤合成变化反映在可见表型（眼睛颜色）中的唯一模型系统。这些研究集中在两个果蝇蛋白质，醛糖还原酶和栗色样+（ma- 1+）蛋白，它们分别参与H4 B和MoCo的合成。从部分氨基酸分析中鉴定的表达序列标签（EST）将用于获得编码醛糖还原酶的分子克隆。将使用醛糖还原酶克隆作为探针，以确定醛糖还原酶基因的细胞遗传学基因座。醛糖还原酶的细胞遗传学位点的知识将允许突变分析，以评估蛋白质的参与H4 B途径。多克隆抗血清提出的栗色样（ma-1）肽将被用来遵循标准纯化的栗色样蛋白，一个假定的半胱氨酸转硫酶，和第一个真核细胞成员的nif-S-样基因家族进行描述。这种抗体也将被用来定位ma-1蛋白在原位和分析现有的ma-1突变体。这些研究将导致更好地了解高等生物中BH 4和MoCo生物合成的终端步骤。

In born errors in the biosynthesis of the pterin cofactors tetrahydrobiopterin (H4B) and molybdopterin (MoCo) are associated with serious human diseases. Genetic variations in the synthesis of H4B have been associated with serious human diseases. Genetic variations in the synthesis of H4B have been associated with diseases such as atypical phenylketonuria, Parkinson's disease, and dystonias. The importance of H4B to these processes is found in its role as an essential cofactor for phenylalanine, tyrosine and tryptophan hydroxylases, enzymes that are involved in amino acid degradation and the biosynthesis of catecholamines and serotonin. The MoCo functions as an essential enzymatic cofactor for molybdenum hydroxylase enzymes such as sulfite oxidase and xanthine dehydrogenase. Genetic deficiencies in the biosynthesis of the MoCo ar3e associated with a severely debilitating neurological disorder, molybdenum cofactor deficiency, and with xanthinuria, a malady of purine metabolism. The proposed studies utilize Drosophila melanogaster, the only model system in which changes in pterin synthesis are reflected in a visible phenotype (eye color), as a genetic model system for pterin cofactor biosynthesis. The studies center on two Drosophila proteins, aldose reductase and the maroon-like+ (ma- 1+) protein, which are involved, respectively, in the synthesis of H4B and MoCo. Expressed sequence tags (ESTSs) identified from partial amino acid analysis will be used to obtain molecular clones encoding the aldose reductase. Aldose reductase clones will be used as probes to determine the cytogenetic locus of the aldose reductase gene(s). Knowledge of the cytogenetic locus of the aldose reductase will allow mutant analysis to assess the protein's involvement in the H4B pathway. Polyclonal antisera raised to maroon-like (ma-1) peptides will be used to follow the standard purification of the maroon-like protein, a putative cysteine transulfurase, and the first eukaryotic member of the nif-S-like gene family to be described. Such antibodies will also be used to localized the ma-1 protein in situ and to analyze existing ma-1 mutants. These studies will lead to a better understanding of the terminal steps of BH4 and MoCo biosynthesis in higher organisms.