REGULATION OF E COLI CYTOCHROME OXIDASE AND TCA CYCLE

描述：细胞中碳和电子流动的多种细胞途径， 大肠杆菌和其它肠道细菌 根据分子氧是否存在于 细胞环境。 其中包括两种不同的电子流动路径 通过由cyoABCDE编码的细胞色素o和d氧化酶与氧结合， cydAB操纵子，或电子流到任何数量的 厌氧电子受体 碳流动的替代途径 包括在需氧过程中在循环途径中使用TCA循环反应， 在有氧条件下，使用支链和非环状TCA途径 和/或厌氧条件，以及所用的混合酸发酵途径 当不存在电子受体时。 该提案涉及如何 细胞完成有氧/无氧基因的调节， 细胞色素氧化酶和TCA循环途径的基因。 的 细胞有两个不同的调节因子，包括Fnr和ArcA/ArcB 参与这项任务的蛋白质。 它们共同协调基因 转录，以帮助调整碳流与电子流在细胞中， 平衡和优化的增长。 然而，人们对如何使用 基因表达的调节发生在分子水平。 主要目标 这项提案的目的是了解ArcA和Fnr蛋白如何参与 调节cyoABCDE、cydAB、sdhCDAB和icd基因表达。 的 蛋白质与DNA的结合位点将被检查，以了解它们是如何 在转录的抑制或激活中发挥作用。 机制 将研究cydAB基因的微好氧基因控制， TCA循环基因的协调调节。 最后，自动调节 arcA基因将进一步研究，因为arcA蛋白是一个主要的 参与E.杆菌 这些研究 应该提供细胞如何协调途径的详细了解 对于在过渡期间电池内的电子和碳流动， 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.