BRANCHED CHAIN AMINO ACID BIOSYNTHESIS IN E COLI

大肠杆菌中支链氨基酸的生物合成

• 批准号: 2623471
• 负责人: G. WESLEY HATFIELD
• 金额: $ 26.13万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-05-01 至 2001-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2623471
• 关键词: DNA binding protein; Escherichia coli; aminoacid biosynthesis; bacterial genetics; conformation; genetic regulation; genetic transcription

DESCRIPTION: This proposal concerns the mechanism of transcriptional activation by a non-specific (histone-like) DNA binding protein called integration host factor (IHF), originally found and named based on its effect on site-specific integration of phage lambda and since shown to act also as a general regulator of expression of numerous operons. It is based upon the P.I.'s recent evidence that IHF activated the ilvG promotor of the ilvGMEDA operon for branched chain amino acid biosynthesis by a novel gene activation mechanism. He already showed that activation of the ilvG promoter requires binding of IHF to an upstream activation site (UAS1), a separate upstream site called SIDD, and a non cononical -10 region. He also showed that the IHF-binding site activated transcription when located on either face of the helix, thus making it unlikely that IHF interacts with RNAP or a different protein factor. He further substantiated this by substitution of the IHF binding site with the binding site of a heterologous DNA binding and bending protein, the lymphoid enhancer- binding factor LEF-1 activates the E. coli ilvG promoter. Binding and transcriptional activation under these conditions is accompanied by an unwinding of two A-T base pairs in the -10 promoter region. These and other experiments has led him to propose a "DNA structural-transmission model" for regulation of the ilvG promoter by IHF. His proposed new experiments are aimed towards testing a number of predictions of this model.

描述：该提案涉及转录机制 由称为非特异性（组蛋白样）DNA 结合蛋白的激活 整合宿主因子（IHF），最初根据其发现并命名 对噬菌体 lambda 的位点特异性整合的影响，并且已显示出作用 也作为许多操纵子表达的一般调节因子。它是基于 根据 P.I. 最近的证据，IHF 激活了 ilvG 启动子 用于支链氨基酸生物合成的ilvGMEDA操纵子 基因激活机制。他已经证明 ilvG 的激活 启动子需要 IHF 与上游激活位点 (UAS1) 结合， 称为 SIDD 的独立上游站点和非圆锥形 -10 区域。他 还表明，当 IHF 结合位点位于 在螺旋的任一面上，因此 IHF 不太可能相互作用 与 RNAP 或不同的蛋白质因子。他进一步证实了这一点 将 IHF 结合位点替换为 异源DNA结合和弯曲蛋白，淋巴增强子- 结合因子 LEF-1 激活大肠杆菌 ilvG 启动子。绑定和 在这些条件下转录激活伴随着 -10 启动子区域中两个 A-T 碱基对的解旋。这些和 其他实验使他提出了“DNA结构传递” IHF 调控 ilvG 启动子的模型”。他提出了新的 实验的目的是测试一些关于这一点的预测 模型。