AFLATOXIN B1 BIOSYNTHESIS IN ASPERGILLUS PARASITICUS

描述：（改编自研究者摘要）总体目标 这项研究项目的目的是了解 调节寄生曲霉中黄曲霉毒素B1的生物合成。 工作 假设黄曲霉毒素B1的生物合成是在 转录水平。 提出以下具体目标，以测试 该假说：（1）克隆编码催化黄曲霉毒素的酶的基因 生物合成的遗传互补的A。寄生虫突变体（“阻断 突变体”）在黄曲霉毒素生物合成中缺乏独特的酶促步骤 通过用粘粒文库转化来表征该途径;以及（2）表征该途径的特征。 克隆基因的遗传组织和表达：a）核苷酸 序列分析，B）Southern和北方分析，c）S-1核酸酶 分析，和d）横向交变场凝胶电泳（TAFE）。 人们希望阐明控制这种合成代谢的机制， 途径将提供抑制黄曲霉毒素生物合成的靶点， 调整监管方案。 从长远来看，这可能会导致 通过施用抗氧化剂来预防收获前黄曲霉毒素生成 该途径的生物/化学抑制剂，通过 非产黄曲霉菌，或宿主植物的遗传修饰。 以来 次级代谢产物的转录调控可能涉及共同的 不同真核生物属之间的调节元件，黄曲霉毒素 途径也可以提供一个模型，了解生物合成 影响公众健康的其他真菌毒素和有毒次级代谢物 和食品安全。

DESCRIPTION: (Adapted from the investigator's abstract) The overall goal of this research project is to understand the molecular mechanisms which regulate aflatoxin B1 biosynthesis in Aspergillus parasiticus. The working hypothesis is that aflatoxin B1 biosynthesis is regulated at the transcriptional level. The following specific aims are proposed to test this hypothesis: (1) Clone genes encoding enzymes which catalyze aflatoxin biosynthesis by genetic complementation of A. parasiticus mutants ("blocked mutants") deficient in unique enzymatic steps in the aflatoxin biosynthetic pathway by transformation with a cosmid library; and (2) characterize the genetic organization and expression of the cloned genes by: a) nucleotide sequence analysis, b) Southern and Northern analysis, c) S-1 nuclease analysis, and d) transverse alternating field gel electrophoresis (TAFE). It is hoped that elucidation of the mechanisms controlling this anabolic pathway will provide targets for inhibition of aflatoxin biosynthesis by alternation of the regulatory scheme. In the long term, this may lead to prevention of preharvest aflatoxigenesis by application of biological/chemical inhibitors of this pathway, competitive exclusion by nonaflatoxigenic aspergilli, or genetic modification of host plants. Since transcriptional regulation of secondary metabolites may involve common regulatory elements among different eukaryotic genera, the aflatoxin pathway may provide a model for also understanding the biosynthesis of other mycotoxins and toxic secondary metabolites that impact public health and food safety.