REGULATION OF E COLI CYTOCHROME OXIDASE AND TCA CYCLE

描述：碳和电子在细胞内流动的各种途径 大肠杆菌和其他肠道细菌中的细菌是 根据分子氧是否存在而区别使用 细胞环境。这包括两条截然不同的电子流动路径。 通过由cyoABCDE编码的细胞色素o和d氧化酶与氧 CydAB操纵子，或电子流向任何数量的 厌氧电子受体。碳流的替代途径 包括在有氧过程中在循环路径中使用TCA循环反应 分枝和非循环TCA途径在有氧条件下的使用 和/或厌氧条件，以及所使用的混酸发酵途径 当不存在电子受体时。这项提案解决了如何 细胞完成对这两个基因的有氧/无氧调节 细胞色素氧化酶，以及TCA循环途径的基因。这个 CELL有两个不同的调节子，由FNR和Arca/ArcB组成 参与这一任务的蛋白质。它们共同协调基因 转录，以帮助调节碳流与细胞内的电子流，以 平衡优化增长。然而，人们对此知之甚少 基因表达的调控发生在分子水平上。主要目标是 了解ArcA和FNR蛋白是如何参与 在调节cyoABCDE、cydAB、sdhCDAB和ICD基因表达方面。这个 将检查蛋白质与DNA的结合部位，以了解它们是如何 转录抑制或激活转录的功能。该机制的目的是 将研究微氧基因对cydAB基因的控制，以及 协调TCA循环基因的调控。最后，自动监管 由于Arca蛋白是一种主要的 在大肠杆菌中参与好氧厌氧开关。这些研究 应该提供对细胞如何协调通路的详细理解 在过渡期间电池内的电子和碳流 富氧和限氧条件。

DESCRIPTION: A variety of cellular pathways for carbon and electron flow in the bacterium Escherichia coli and in other enteric bacteria are differentially employed depending on whether molecular oxygen is present in the cell environment. These include two distinct pathways for electron flow to oxygen via the cytochrome o and d oxidases encoded by the cyoABCDE and cydAB operons, respectively, or electron flow to any of a number of anaerobic electron acceptors. The alternative pathways for carbon flow include use of the TCA cycle reactions in a cyclic pathway during aerobic conditions, use of the branched and non-cyclic TCA pathway during aerobic and/or anaerobic conditions, and the mixed acid fermentation pathway used when no electron acceptors are present. This proposal addresses how the cell accomplishes the aerobic/anaerobic regulation of genes for the two cytochrome oxidase enzymes, and the genes of the TCA cycle pathway. The cell has two distinct regulators, comprised of the Fnr and the ArcA/ArcB proteins that participate in this task. Together, they coordinate gene transcription to help adjust carbon flow with electron flow in the cell for balanced and optimal growth. However, little is known about how the regulation of gene expression occurs at the molecular level. The major aims of this proposal are to understand how the ArcA and Fnr proteins participate in regulating cyoABCDE, cydAB, sdhCDAB, and icd gene expression. The binding sites of the proteins to DNA will be examined to understand how they function in repression or activation of transcription. The mechanism for microaerobic gene control of the cydAB genes will be studied, as will the coordinate regulation of the TCA cycle genes. Finally, the autoregulation of the arcA gene will be further examined since the ArcA protein is a major participant in the aerobic anaerobic switch in E. coli. These studies should provide a detailed understanding of how the cell coordinates pathways for electron and carbon flow within the cell during transition between oxygen rich and oxygen limiting conditions.