REGULATION OF THE E COLI CYTOCHROME OXIDASE GENES

本研究项目的目标是阐明其机制 负责控制细胞色素氧化酶的表达 肠上皮细胞中的细胞色素D氧化酶（cydAB）基因 细菌，大肠杆菌。这两个操纵子编码两个选择性的 用于氧还原的酶复合物。 它们最佳地表示为 需氧或微需氧条件，并允许细胞产生 随后通过质子产生ATP的化学渗透势 转位ATP酶。 该电势也用于质子驱动 溶质摄取和细胞运动。 由cyoABCDE编码的酶和 cydAB基因是许多其他细胞色素氧化酶的代表。 微生物，包括肠道细菌，各种兼性土壤 细菌和至少一些专性好氧细菌。 我们 建议研究细胞色素o（cyoABCDE）的调节， 细胞色素d（cydAB）氧化酶基因。大肠杆菌作为一个模型来理解 这些需氧细胞的功能是受调节的， 环境条件 关于其机制还知之甚少 负责这个控制。 我们将研究fnr，arcA， 和himA基因产物，以便更好地了解 他们采取行动的机制。 细胞色素d氧化酶（cydAB）的控制 基因表达将通过定位诱变和筛选来检查 顺式作用的调节突变。 DNA结合研究将在 进行定位Fnr和ArcA蛋白的调节位点。 类似的研究也将与细胞色素氧化酶（cyoABCDE） 基因，以确定Fnr和ArcA蛋白如何影响其表达。 CAP在cyoABCDE表达中的作用也将被检查。 到 了解arcA和arcB基因产物的水平如何变化， 细胞中，将使用lacZ融合载体系统检查它们的表达。 最后，研究了氧浓度和生长速率对cyoABCDE的影响 和cydAB基因表达将进行测试，以更好地了解 E. coli细胞。

The goal of this research project is to elucidate the mechanisms responsible for controlling expression of the cytochrome o oxidase (cyoABCDE) and cytochrome d oxidase (cydAB) genes in the enteric bacterium, Escherichia coli. These two operons encode the two alternative enzyme complexes for oxygen reduction. They are expressed optimally under aerobic or micro-aerobic conditions and allow the cell to generate a chemiosmotic potential for subsequent ATP generation via the proton translocating ATPase. This potential is also used for proton driven solute uptake and for cell motility. The enzymes encoded by cyoABCDE and cydAB genes are representative of the cytochrome oxidases in many other microorganisms including the enteric bacteria, various facultative soil bacteria and for at least some of the obligate aerobic bacteria. We propose to study the regulation of the cytochrome o (cyoABCDE) and cytochrome d (cydAB) oxidase genes of E. coli as a model to understand how these aerobic cell functions are regulated in response change in environmental conditions. Little is yet known about the mechanisms responsible for this control. We will study the role of the fnr, arcA, and himA gene products in these processes to better understand the mechanisms by which they act. Control of cytochrome d oxidase (cydAB) gene expression will be examined by localized mutagenesis and screening for cis-acting regulatory mutations. DNA binding studies will be performed to locate regulatory sites for the Fnr and ArcA proteins. Similar studies will also be done with the cytochrome o oxidase (cyoABCDE) genes to determine how the Fnr and ArcA proteins affect their expression. The role of CAP in cyoABCDE expression will also be examined. To understand how the levels of the arcA and arcB gene products vary in the cell, their expression will be examined using lacZ fusion vector systems. Finally, the effect of oxygen concentration and growth rate on cyoABCDE and cydAB gene expression will be tested to better understand the physiology of oxygen use by E. coli cells.