REGULATION OF GLUTAMINE SYNTHETASE IN STREPTOMYCES

链霉菌合成了70多种具有重要医学价值的物质 抗生素以及抗肿瘤和抗寄生虫剂。这些化合物 在营养限制期间以次生代谢产物的形式产生 产孢子的启动。然而，监管的机制 链霉菌次生代谢和产孢量的启动 明白了。谷氨酰胺合成酶(GS)的合成 在氮素同化过程中，抗生素放线菌素增加 天蓝色链霉菌在氮素限制条件下。对该事件的调查 在其他细菌系统中对GS的调节已经确定了全球 激活基因表达以响应氮的调控网络 可用性。GS基因将被用作研究调控的句柄 氮素作用下基因表达变化的机制 链霉菌的限量。将使用两种方法来调查 天蓝色链霉菌GS基因的调控。首先，天蓝色苏云金杆菌 本实验室已克隆的结构基因(GlnA)将被 确定glnA启动子和编码区的物理特征。 其次，涉及GS调控的因素将从基因上确定 通过分离突变株来改变合成GS的能力。这个 GlnA克隆的DNA将被用来研究 GlnA启动子与遗传鉴定的GS调节蛋白RNA 聚合酶和小分子含氮化合物。一种对 链霉菌GS氮素调控机制的研究进展 允许使用合理的战略来增加石油产量 抗生素和其他次生代谢物，以及新菌的分离 次生代谢物。此外，应该有可能开发一种 更好地了解 链霉菌次生代谢和产孢量的启动。

Streptomyces species synthesize more than 70 medically important antibiotics as well as antitumor and antiparasitic agents. These compounds are produced as secondary metabolites during nutritional limitation and the initiation of sporulation. However, the mechanisms which regulate the initiation of secondary metabolism and sporulation in Streptomyces are not understood. The synthesis of both glutamine synthetase (GS), a key enzyme in nitrogen assimilation, and the antibiotic, actinorhodin, are increased during nitrogen limitation in S. coelicolor. Investigations of the regulation of GS in other bacterial systems have identified global regulatory networks which activate gene expression in response to nitrogen availability. The GS gene will be used as a handle for studying regulatory mechanisms responsible for alterations in gene expression during nitrogen limitation in Streptomyces. Two approaches will be used to investigate the regulation of the GS gene in S. coelicolor. First, the S. coelicolor GS structural gene (glnA) which has been cloned in this laboratory will be physically characterized to determine the glnA promoter and coding region. Secondly, factors involved in GS regulation will be identified genetically by the isolation of mutants altered in the ability to synthesize GS. The glnA cloned DNA will then be used to study the interactions between the glnA promoter and the genetically identified GS regulatory proteins, RNA polymerase and small nitrogen-containing compounds. An understanding of the mechanisms which mediate nitrogen regulation of GS in Streptomyces will allow rational strategies to be used for the increased production of antibiotics and other secondary metabolites, and the isolation of novel secondary metabolites. Furthermore, it should be possible to develop a better understanding of the regulatory mechanisms involved in the initiation of secondary metabolism and sporulation in Streptomyces.