Structure-Based Design of Small Molecules for Aspartylglucosaminuria

天冬氨酸氨基葡萄糖尿症(AGU)是一种溶酶体储存性疾病，由代谢紊乱引起 糖蛋白降解。AgU导致几乎所有ALL的溶酶体中糖天冬酰胺积聚 细胞类型，有严重的临床症状，如进行性神经变性和智力低下， 面部特征粗糙，骨骼异常，结缔组织病变。AGU突变发生在 糖基天冬酰胺酶(GA)的基因，这是一种水解糖天冬酰胺所需的溶酶体酶。阿古有 全世界都有报道，到目前为止已经发现了26种不同的AGU等位基因，但仍然没有治疗方法 疾病。然而，在过去几年中，在鉴定和鉴定方面取得了重大进展。 AGU致病突变的特征。因此，一种有效的AGU疗法的开发将使 这种遗传病适合对新生儿进行筛查，以便及早治疗。我们的结晶学研究 GA揭示了一个表面环(称为前体P-环)阻止了成熟水解酶的催化中心。 因此，为了打开催化中心，需要自体蛋白分解来去除这个P-环。尽管如此， AgU突变会导致GA前体的错误处理和错误定位，从而阻止它们的自我激活 用于水解酶活性。GA和AGU分子的高分辨结构研究将大大提高 我们对这些AGU突变的结构性后果的理解，但到目前为止一直受到阻碍 由于无法获得足够量的高纯度人GA。尽管如此，我们还是克服了 这一障碍是通过纯化和结晶细菌GA来实现的，已被证明具有相同的 结构特征，并使用相同的机制自动激活其水解酶活性。我们的预赛 结果表明，具有类似甘氨酸结构的小分子可以促进自身蛋白分解和 AGU突变体的水解酶活性。基于我们在遗传算法自动处理方面的最新进展，我们在 这一应用1)表征AGU突变的分子发病机制；2)推进我们的结构 和GA自身蛋白分解激活的机制研究；3)研究AGU的结构后果 突变；以及4)开发小分子来刺激AGU分子的自动加工。宽阔的，长的- 本申请的术语目标是开发小分子作为治疗药物来改善AGU 错误处理和错误定位缺陷，从而减轻AGU患者及其家人的痛苦。

Aspartylglucosaminuria (AGU) is a lysosomal storage disease caused by a metabolic disorder in glycoprotein degradation. AGU results in accumulation of glycoasparagines in the lysosomes of virtually all cell types, with severe clinical symptoms such as progressive neurodegeneration and mental retardation, coarse facial features, skeletal abnormalities, and connective tissue lesions. AGU mutations occur in the gene for glycosylasparaginase (GA), a lysosomal enzyme required to hydrolyze glycoasparagines. AGU has been reported worldwide, with 26 different AGU alleles found so far, but still no treatment available for this disease. However, during the past few years, there has been significant progress in the identification and characterization of AGU causative mutations. Thus development of an effective AGU therapy would make this genetic disease amenable to newborn screening for an early treatment. Our crystallographic studies on GA reveal that a surface loop (named precursor P-loop) blocks the catalytic center of mature hydrolase. Autoproteolysis is thus required to remove this P-loop in order to open up the catalytic center. Nonetheless, AGU mutations cause misprocessing and mistargeting of GA precursors, thus prevents their autoactivation for the hydrolase activity. High-resolution structural studies of GA and AGU molecules will greatly enhance our understanding of the structural consequences of these AGU mutations but have so far been hampered by the inability to obtain sufficient amounts of highly purified human GA. Nonetheless, we have overcome this hurdle by purifying and crystallizing bacterial GA, which has been demonstrated to have identical structural features and use the same mechanism to autoactivate its hydrolase activity. Our preliminary results indicate that small molecules with structures similar to glycine can enhance autoproteolytic and hydrolase activity of AGU mutants. Building on our recent progress on GA autoprocessing, we propose in this application to 1) characterize molecular pathogenesis of AGU mutations; 2) push forward our structural and mechanistic studies of GA autoproteolytic activation; 3) study structural consequences of AGU mutations; and 4) develop small molecules to stimulate autoprocessing of AGU molecules. The broad, long- term objective of this application is to develop small molecules as therapeutics to ameliorate the AGU misprocessing and mistargeting defect and thus alleviate the suffering of AGU patients and their families.