Structure/Function Studies of Quinone Reductase 2

描述（由申请人提供）：拟议工作的目的是使用酶、结构、生物化学和生物学方法的组合来研究醌还原酶2（QR 2）的结构/功能关系。QR 2的生物学功能实际上仍然未知，即使其同源物醌还原酶1（QR 1）被很好地表征。我们最近的研究表明，醌还原酶2（QR 2）是许多天然多酚的潜在靶标，包括白藜芦醇类似物，黄酮类化合物，查尔酮类化合物和一些香豆素衍生物。QR 2还在还原CB 1954和儿茶酚醌如肾上腺色素的硝基中具有活性。通过RNAi方法敲低QR 2进一步证明，白藜芦醇处理的细胞和QR 2敲低的细胞表现出相似的性质：对醌毒性的抗性、抗氧化酶的表达增加和增殖速率降低。基于这些研究，我们假设QR 2具有非常不同的功能，从QR 1的虚拟的独特性质，底物特异性，相互作用的蛋白质伴侣，抑制剂除了QR 1。我们进一步假设，QR 2是一个潜在的关键调节器，直接或间接地，在抗氧化酶的表达，如过氧化氢酶和谷胱甘肽还原酶。因此，我们建议通过底物特异性研究来研究QR 2的催化性质，特别是对神经毒性醌和药物代谢物的催化活性;抑制剂特异性研究;阐明QR 2与其底物和抑制剂复合物的结构;通过蛋白质组学方法和潜在的体内电子供体鉴定相互作用的蛋白质;以及QR 2敲除细胞系的蛋白质表达谱。全面的方法将阐明QR 2的独特催化特性和生物学功能，以及QR 2多态性与某些神经系统疾病的关系，因为QR 2多态性与特发性帕金森病，精神分裂症，酒精戒断症状和氯氮平诱导的粒细胞增多症有关。

DESCRIPTION (provided by applicant): The aim of the proposed work is to use a combination of enzymatic, structural, biochemical, and biological approaches to study the structural/function relationship of quinone reductase 2 (QR2). The biological functions of QR2 are still virtually unknown, even though its close homolog, quinone reductase 1 (QR1), is well characterized. Our recent studies indicate that quinone reductase 2 (QR2) is the potential target of many natural polyphenols, including resveratrol analogs, flavonoids, chalconoids and some coumarin derivatives. QR2 is also active in the reduction of nitro groups of CB1954 and catechol quinones such as adrenochrome. QR2 knock down by RNAi method further demonstrated that resveratrol treated cells and QR2 knockdown cells exhibit similar properties: resistance to quinone toxicity, increased expression of anti-oxidant enzymes, and reduced proliferation rate. Based on those studies, we hypothesize that QR2 possesses very different functions from QR1 by virtual of its unique properties in substrate specificities, interacting protein partners, and inhibitors apart from QR1. We further hypothesize that QR2 is potentially a critical regulator, directly or indirectly, in the expression of antioxidant enzymes, such as catalase and glutathione reductases. Therefore, we propose to study the catalytic properties of QR2 with substrate specificity studies, especially the catalytic activity towards neurotoxic quinones and drug metabolites; inhibitor specificity studies; elucidation of QR2 structures in complex with its substrates and inhibitors; identification of interacting proteins by proteomics approach and potential in vivo electron-donors; and protein expression profiling of QR2 knockdown cell lines. The comprehensive approach will shed light on the unique catalytic properties and biological functions of QR2 and the understanding of QR2 polymorphism in relationship with certain neurological diseases, as QR2 polymorphism has been associated with idiopathic Parkinson's disease, schizophrenia, alcohol withdrawal symptoms and clozapine-induced aranulocytosis.