Cytochrome P450 Enzymes: Identification, Diversity, and Potential Functions in Marine Invertebrates

细胞色素P450酶可能是自然界中最多样化的蛋白质家族。它们存在于迄今为止所研究的所有生物体中，并且具有广泛的代谢外来化学物质（异种生物）和内源性分子（如类固醇和脂肪酸）的能力。P450多样化的驱动力之一被认为是饮食中有毒化学物质的出现，即所谓的“植物-动物战争”假说。在哺乳动物中，一个个体中可能存在一百种或更多的P450形式，每种形式都有自己的代谢能力。同样，昆虫似乎有大量的P450形式，其中一些涉及杀虫剂和膳食植物的化感化学抗性。海洋无脊椎动物也有可证实的P450酶活性，这是由暴露于污染物诱导的，尽管几乎没有人知道海洋无脊椎动物对饮食化学物质的解毒酶的作用。关于这组酶的新信息可能有助于解释个别物种的饮食和代谢方面，以及确定影响对其他外源性暴露的耐受性的因素。研究者建议利用分子克隆方法从代表三个不同门的几种海洋无脊椎动物物种中分离和鉴定新的细胞色素P450基因（Aim 1）。这些数据将为海洋无脊椎动物中这种大型蛋白质超家族的多样性提供首次估计。将在野外采集的物种和受控的实验室饲养实验中研究该家族中选定的新蛋白的基因表达诱导（目标2）。将生产几种新形式的抗体，用于设计敏感的免疫学试验，以测量毒素暴露对P450的诱导作用（目标3）。由于目前还没有已知的海洋无脊椎动物P450序列，这些研究将为这些重要酶的多样性提供急需的信息。研究结果将有助于比较海洋和陆地生物之间解毒酶的进化和功能。最终目标是开发方法，以测试暴露于天然和人工毒物后的物种特异性反应。

9631128 Snyder Cytochrome P450 enzymes are perhaps the most diverse family of proteins in nature. They are found in all organisms thus far examined and have extensive abilities to metabolize foreign chemicals (xenobiotics) and endogenous molecules such as steroids and fatty acids. One of the driving forces for P450 diversification is thought to be the appearance of toxic chemicals in the diet, the so-called plant-animal warfare" hypothesis. In mammals, one hundred or more P450 forms may exist in a single individual, each with its own metabolic capabilities. Likewise, insects appear to have a large number of P450 forms, some involved in insecticide and dietary plant allelochemical resistance. Marine invertebrates also have demonstrable P450 enzymatic activities that are inducible by exposure to pollutants, though virtually nothing is known about the role of detoxification enzymes in marine invertebrate to dietary chemicals. New information on this group of enzymes may help explain aspects of individual species diet and metabolism as well as identify factors that affect tolerance to other xenobiotic exposures. The investigator proposes to utilize molecular cloning approaches to isolate and identify new cytochrome P450 genes from several marine invertebrate species representing three different Phyla (Aim 1). Those data will provide the first estimate of the diversity of this large protein superfamily among marine invertebrates. The induction of gene expression for selected new proteins belonging to this family will be studied in both field collected species and in controlled laboratory feeding experiments (Aim 2). Antibodies will be produced to several new forms for the design of sensitive immunological assays to measure P450 induction in response to toxin exposures (Aim 3). Since there are currently no marine invertebrate P450 sequences known, these studies will provide much needed information about the diversity of these important enzymes. The results will allow comparisons concer ning the evolution and functions of detoxification enzymes between marine and terrestrial organisms. An eventual goal is the development of methods that will test species-specific responses following exposure to natural and artificial toxicants.