Collaborative Research: A Comprehensive Study of the Structure, Function, and Diversity of Detoxification Enzymes (CYP2B) in Mammalian Herbivores (Neotoma)

在每顿饭中，成千上万种以植物为食的哺乳动物都面临着被它们的食物产生的天然毒素毒死的可能性。哺乳动物食草动物的普遍觅食习惯，每天吃许多不同的植物物种，被认为是由于它们的肝酶的限制。多面手被假设拥有一种“万能”式的解毒系统，该系统由能够代谢多种植物毒素的肝酶组成，但催化效率较低。相比之下，专家们被认为具有解毒酶，对有限数量的毒素具有更高的效率。在没有任何实验支持的情况下，这种与饮食专业化有关的生化权衡概念基本上已经成为教条。这项研究将利用从模式物种和人类的药物代谢研究中获得的哺乳动物解毒酶的广泛知识，以及最好的哺乳动物食草性野生啮齿动物模型的可用性。长期目标是通过对食草性林木动物细胞色素P450亚家族2B(细胞色素P450亚家族2B)的肝酶的重点研究，确定饮食暴露于植物毒素如何塑造哺乳动物的解毒系统。这次合作研究的具体目标是：1.)在氨基酸水平上研究木鱼中的CYP2B酶的特性。2.)使用新的代谢组学方法来确定林蛙饲料中的关键P450底物，并比较林蛙CYP2B酶对植物毒素的新陈代谢。3.)使用定点突变和X-射线结晶学对Wooddrat CYP2B酶进行结构-功能分析。这项工作将利用尖端的生化和结构生物学方法来解决一个长期存在的假说，以产生第一次对野生草食动物的CYP2B酶的详细检查，识别底物，并比较酶的功能。最终的目标是解决与植物毒素形成复合体的木犀酶的晶体结构。目前，关于哺乳动物解毒酶的知识还很初级。这项工作有可能有助于了解药物在人类体内的新陈代谢，因为这些研究人员提供了有关木犀酶的初步数据。此外，树木是大自然的历史学家；它们储存食物的行为有助于理解过去35,000年来西南沙漠发生的自然变化。犹他州自然历史博物馆将开发一个关于树木生态及其对社会重要性的互动展示。PI将指导新一代受训人员(高中生到博士后研究员)进行跨学科研究。该奖项由化学部的生命过程化学项目共同资助。

At every meal, thousands of species of plant-eating mammals confront the possibility of being poisoned by the natural toxins produced by their food. The generalized foraging habit of mammalian herbivores, eating many different plant species on a daily basis, is thought to result from limitations of their liver enzymes. Generalists are hypothesized to have a "jack of all trades" style of detoxification system that consists of liver enzymes able to metabolize a wide array of plant toxins but with low catalytic efficiency. In contrast, specialists are thought to have detoxification enzymes with enhanced efficiency towards a restricted number of toxins. This concept of biochemical tradeoffs with respect to dietary specialization has essentially become dogma without any experimental support. This research will capitalize on the extensive knowledge of mammalian detoxification enzymes gained from studies of drug metabolism in model species and humans, as well as on the availability of a superlative wild rodent model of mammalian herbivory. The long-term objective is to determine how dietary exposure to plant toxins has shaped the mammalian detoxification system through a focused study of liver enzymes in the cytochrome P450 subfamily 2B (CYP2B) in herbivorous woodrats (Neotoma). The specific goals of this collaborative research are: 1.) Characterize the CYP2B enzymes in woodrats at the amino acid level. 2.) Use new metabolomic approaches to identify key P450 substrates in diets of woodrats and compare metabolism of plant toxins by woodrat CYP2B enzymes. 3.) Conduct structure-function analyses using site-directed mutagenesis and X-ray crystallography of woodrat CYP2B enzymes. The work will address a longstanding hypothesis by drawing upon cutting-edge biochemical and structural biology approaches to generate the first detailed examination of CYP2B enzymes of wild herbivores, identify substrates, and compare enzyme function. The ultimate goal is to solve the crystal structures of woodrat enzymes in complex with plant toxins. Currently, knowledge of detoxification enzymes of mammals is rudimentary. The work has the potential to contribute to the understanding of drug metabolism in humans given preliminary data of these investigators on woodrat enzymes. In addition, woodrats are nature's historians; their behavior of storing food has facilitated an understanding of the natural changes that have taken place in the desert southwest over the last 35,000 years. An interactive display about the ecology of woodrats and their importance to society will be developed at the Utah Museum of Natural History. The PIs will mentor a new generation of trainees (high school students through postdoctoral fellows) in interdisciplinary research. This award is co-funded by the Chemistry of Life Processes Program in the Division of Chemistry.