GENETIC CONTROL OF NITRATE RESPIRATION IN E. COLI

对厌氧的适应是一种复杂的生理反应 由兼性细菌，如大肠杆菌。一个重要的方面是 这种适应是呼吸交替末端电子的能力。 取代氧的受体。硝酸盐是一种重要的交替电子 受体，并合成呼吸酶，硝酸还原酶，是 在无氧条件下由硝酸盐诱导的。此外，发挥作用 硝酸盐呼吸抑制其他兼性呼吸的形成 和发酵途径。这个项目的长期目标是 识别和描述控制 硝酸还原酶和其他兼性呼吸酶的形成。 这项提议描述了一种分子遗传学方法来理解 硝酸盐呼吸的控制。它主要关注NAR(Ch1C)基因， 它同时包含硝酸盐的结构基因和调控基因 还原酶。将结合缺失详细检查nar基因座 小麦品种的作图、互补分析、分子克隆和检测 基因-蛋白质关系。NAR点、插入和 将通过各种方法和筛选来分离缺失突变 程序。这些突变将被用来构建详细的 NAR区精细结构遗传图谱。选定的突变将是 基因互补测试，允许精细结构的分裂 映射到互补组。将克隆NAR区域并 通过限制性内切酶图谱和Southern杂交分析。这些研究 将允许遗传精细结构的相关性，互补 和物理图谱，并将用于精确定位NAR的基因 区域。硝酸还原酶的结构基因将通过 硝酸还原酶生产用突变株和亚克隆的检测 多肽。最后，操纵子融合将被用来分析 硝酸还原酶和其他兼性呼吸基因的调节， 也是为了测试NAR调控基因特定突变的效果。

Adaptation to anaerobiosis is a complex physiological response demonstrated by facultative bacteria such as Escherichia coli. One important aspect of this adaptation is the ability to respire alternate terminal electron acceptors in place of oxygen. Nitrate is an important alternate electron acceptor, and synthesis of the respiratory enzyme, nitrate reductase, is induced by nitrate in the absence of oxygen. In addition, functioning nitrate respiration inhibits the formation of other facultative respiratory and fermentation pathways. The long-range goal of this project is to identify and characterize regulatory elements and networks that control the formation of nitrate reductase and other facultative respiratory enzymes. This proposal describes a molecular genetic approach toward understanding the control of nitrate respiration. It focuses on the nar (ch1C) locus, which contains both structural genes and regulatory genes for nitrate reductase. The nar locus will be examined in detail, combining deletion mapping, complementation analysis, molecular cloning and examination of gene-protein relationships. A collection of nar point, insertion and deletion mutations will be isolated by a variety of methods and screening procedures. These mutations will be used to construct a detailed fine-structure genetic map of the nar region. Selected mutations will be tested for genetic complementation, allowing division of the fine-structure map into complementation groups. The nar region will be cloned and analyzed by restriction mapping and Southern blot analysis. These studies will allow the correlation of the genetic fine-structure, complementation and physical maps, and will serve to precisely locate the genes of the nar region. The structural genes for nitrate reductase will be identified by testing various mutants and subclones for production of nitrate reductase polypeptides. Finally, operon fusions will be used to analyze the regulation of nitrate reductase and other facultative respiratory genes, and also to test the effects of specific mutations in nar regulatory genes.