REGULATION OF THE E COLI CYTOCHROME OXIDASE GENES

这项研究项目的目的是阐明其作用机制。 负责控制细胞色素o氧化酶的表达 (CyoABCDE)和细胞色素d氧化酶(CydAB)基因 细菌，大肠埃希菌。这两个操作子编码了两个备选方案 用于氧还原的酶复合体。它们在以下条件下得到最佳表达 好氧或微好氧条件，并允许细胞产生 通过质子产生后续三磷酸腺苷的化学渗透势 转移ATPase。这种势能也用于质子驱动。 溶质摄取和细胞运动。CyoABCDE编码的酶和 CydAB基因是细胞色素氧化酶的代表基因。 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)和 以大肠杆菌的细胞色素d(CydAB)氧化酶基因为模型来了解 这些有氧细胞的功能是在响应变化中调节的 环境条件。目前对这种机制还知之甚少。 对这一控制负责。我们将研究FNR，Arca， 和HIMA基因产物在这些过程中更好地理解 他们采取行动的机制。细胞色素d氧化酶(CydAB)的调控 基因表达将通过局部突变和筛选进行检测 顺式作用的调控突变。DNA结合研究将是 用来定位FNR和ARCA蛋白的调控位点。 对细胞色素o氧化酶(Cyoabcde)也将进行类似的研究。 基因来确定FNR和ARCA蛋白如何影响它们的表达。 CAP在cyoABCDE表达中的作用也将被研究。至 了解arca和arcB基因产物的水平在 细胞中，将使用LacZ融合载体系统检测它们的表达。 氧浓度和生长速率对细胞周期的影响 并将测试cydAB基因的表达，以更好地了解 大肠杆菌细胞利用氧气的生理学。

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.