MECHANISM OF CARBOHYDRATES TRANSPORT IN BACTERIA

磷酸烯醇丙酮酸：糖磷酸转移酶系统（PTS）是一个复杂的 鼠伤寒沙门氏菌和大肠杆菌中的酶系统 催化伴随的跨膜转运和磷酸化 糖的底物。 它还规定了各种 不通过PTS催化的基团移位吸收的碳源 机制 我们实验室的研究提供了关于 PTS在催化和调节 碳代谢 我们已经克隆并测序了许多编码 PTS蛋白和调节其表达的蛋白， 进行了广泛的分子遗传学和生物化学分析， 他们的行动机制。 这些研究使我们能够定义 PTS介导的蛋白质磷酸化的变构机制 调节非PTS碳水化合物渗透酶的活性，分解代谢 酶和腺苷酸环化酶。 最近，我们的研究表明， 果糖（fru）调节子异常复杂， （FruR）与其他果糖特异性蛋白一起调节 沙门氏菌中涉及的数百种编码酶的基因的转录 碳代谢的发病机制和中枢途径（糖酵解， Krebs循环、乙醛酸分流、异源生成和电子转移）。 拟议研究的目的是扩大我们对 fru调节子，果糖特异性PTS蛋白及其参与 糖转运和转录调控。 使用沙门氏菌 鼠伤寒沙门氏菌，生物化学和分子遗传学相结合的方法将 如下： 1. 我们会对fruR基因进行测序， frur 用于物理化学、DNA结合和体外 转录 问题研究 其他蛋白质被认为 参与监管将 同样的准备。 目标 待研究的基因包括 FRU调节子 受到FruR的负调控， 那些编码 主要代谢途径的酶， 积极 由FruR监管。 可能参与的 酶 果糖PTS和蛋白质磷酸化的作用 测试. 2. 我们将描述fru的各个组成部分 调节子 包括编码重复拷贝的 PTS能量 偶联蛋白和渗透酶。 我们还将 表征 酶IIIfru-MR-FPr和酶IIfru 蛋白质，以便 定义结构-功能 各种关系 域. x射线衍射 研究（将进行） 将补充 分子遗传生化 研究提出。

The phosphoenolpyruvate:sugar phosphotransferase system (PTS) is a complex enzyme system which in Salmonella typhimurium and Escherichia coli catalyzes the concomitant transmembrane transport and phosphorylation of its sugar substrates. It also regulates the utilization of a variety of carbon sources not taken up via the PTS-catalyzed group translocation mechanism. Studies in our laboratory have provided information regarding the mechanisms by which the PTS functions in catalysis and regulation of carbon metabolism. We have cloned and sequenced many of the gene encoding PTS proteins and proteins which regulate their expression, and have conducted extensive molecular genetic and biochemical analyses to define their mechanisms of action. These studies have allowed us to define the allosteric mechanism by which PTS-mediated protein phosphorylation regulates the activities of non-PTS carbohydrate permeases, catabolic enzymes and adenylate cyclase. Recently, our studies have shown that the fructose (fru) regulon is exceptionally complex and that the fru repressor (FruR) together with other fructose-specific proteins regulates transcription of hundreds of genes encoding enzymes involved in Salmonella pathogenesis and central pathways of carbon metabolism (glycolysis, the Krebs cycle, the glyoxylate shunt, gluconeogenesis, and electron transfer). The purpose of the proposed research is to extend our understanding of the fru regulon, the fructose-specific PTS proteins and their involvement in sugar transport and transcriptional regulation. Employing Salmonella typhimurium, a combined biochemical and molecular genetic approach will be taken as follows: 1. We will sequence the fruR gene and overproduce and purify FruR for physicochemical, DNA binding and in vitro transcription studies. Other proteins believed to be involved in regulation will similarly be prepared. Target genes to be studied include those of the fru regulon which are negatively regulated by FruR as well as those encoding enzymes of central metabolic pathways which are positively regulated by FruR. The possible involvement of the enzymes of the fructose PTS and protein phosphorylation will be tested. 2. We will characterize the various components of the fru regulon including cryptic genes encoding duplicate copies of PTS energy coupling proteins and permeases. We will also characterize the Enzyme IIIfru-MR-FPr and the Enzyme IIfru proteins in order to define the structure-function relationships of their various domains. X-ray diffraction studies (to be conducted collaboratively) will complement the molecular genetic and biochemical studies proposed.