REGULATION OF ISOLEUCINE/VALINE BIOSYNTHESIS

我们感兴趣的是细胞协调细胞的机制。 其生长所需的各种基因的表达。 的基因 异亮氨酸缬氨酸生物合成分为五个转录 单位 多种分子信号作为表达的效应子 ILV的基因。 这包括ILV特定的监管机构（如 氨基酸终产物和蛋白质）和一般或全局控制（例如 作为ppGpp和蛋白质因子）。 这些分子种类影响ILV基因 通过不同的机制表达（即，转录起始与 衰减）。 效应子的数量和谱反映了 异亮氨酸、亮氨酸和缬氨酸构成了 蛋白质中的氨基酸。 因此，它们的合成代表了 蜂窝资源的主要承诺，并且小区能够 以最佳地调节这些基因的表达， 替代生理条件。 五个基因联合收割机形成ilvGMEDA操纵子，其含有多个 调节位点，以实现其基因的必要平衡， 产品. 调节的主要部位是启动子-衰减子 在ilvG的近端。 操纵子内的次级位点包括： 启动子和内部终止位点。 反式效应子（ppGpp和 蛋白质）似乎调节5 ′启动子的表达。 为了研究操纵子调控的相关因素，我们 将使用我们构建的ilv-galK融合体。 这些质粒 将使用各种技术进行研究。 这将包括：（1） 寡核苷酸诱变;（2）蛋白相互作用的体内分析; （3）RNAP相互作用的体外分析。 此外，我们还定义了一个 启动子上游的一个位点，这是最大表达所必需的 从ILV启动子，并提出分离蛋白质， 本网站 因为基因表达的协调是至关重要的 对于细胞功能，我们认为重要的是确定 实现这种协调的机制。 的基因 异亮氨酸/缬氨酸生物合成形成这样一组。 因为它们的DNA 基因已被分离和表征，它们很容易获得， 详细分析其监管。

We are interested in the mechanism by which a cell coordinates the expression of the various genes required for its growth. The genes for isoleucine valine biosynthesis are separated into five transcriptional units. A variety of molecular signals act as effectors of the expression of the ilv genes. These include both ilv specific regulators (such as the amino acid end products and proteins) and general or global controls (such as ppGpp and protein factors). These molecular species affect ilv gene expression by different mechanisms (ie, transcription initiation vs. attenuation). The number and spectrum of effectors reflects that isoleucine, leucine, and valine constitute an above average percentage of the amino acids present in protein. Thus, their synthesis represents a major commitment of cellular resources and it is essential the cell be able to optimally modulate the expression of these genes in response to alternative physiological conditions. Five the genes combine to form the ilvGMEDA operon, which contains multiple regulatory sites so as to achieve the requisite balance of its gene products. The primary site of regulation is the promoter-attenuator proximal to ilvG. Secondary sites within the operon include: two internal promoters and internal termination sites. The trans effectors (ppGpp and proteins) appear to regulate expression at the 5' promoter. In order to study the factors involved in the regulation of the operon, we will employ the ilv-galK fusions which we have constructed. These plasmids will be studied using a variety of techniques. This will include: (1) oligonucleotide mutagenesis; (2) in vivo analysis of proein interactions; and (3) in vitro analysis of RNAP interactions. Also, we have defined a site upstream of the promoter, which is required for maximal expression from the ilv promoter and propose to isolate the protein(s) that act at this site. Because the coordination of the expression of sets of genes is essential for cellular function, we believe it is important to determine the mechanisms by which this coordination is achieved. The genes for isoleucine/valine biosynthesis form such a set. Because the DNA of these genes has been isolated and characterized, they are readily accessible for detailed analysis of their regulation.