INTERACTIONS BETWEEN DNA AND THE LYSR-TYPE PROTEIN OCCR

DNA 与 LYSR 型蛋白 OCCR 之间的相互作用

• 批准号: 2169678
• 负责人: WILLIAM C FUQUA
• 金额: $ 2.86万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-05-01 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/2169678
• 关键词: DNA binding protein; DNA footprinting; gel mobility shift assay; gene induction /repression; gene interaction; genetic promoter element; genetic transcription; regulatory gene

The process of Agrobacterium tumefaciens of plants is a well studied phenomenon, and is the only bonafide example of natural genetic engineering. The infecting bacterium transfers a fragment of its DNA from a tumor inducing (Ti) plasmid, into the host plant genome. Genes encoded on this fragment direct tumor formation and the synthesis of unusual sugars and amino acids termed opines, which serve as Agrobacterium-specific carbon/nitrogen sources. In turn, the opines stimulate the expression of A. tumefaciens genes involved in their uptake and utilization, conjugal transfer of the Ti plasmid, and a number of other functions that may be involved in tumor colonization. In octopine-type plasmids this induction is mediated at least in part by the LysR-type transcriptional activator OccR, which induces the transcription of these genes in response to the opine octopine and which also autoregulates its own synthesis. One of the targets for OccR regulation is the overlapping, divergently transcribed promoter region between the occ (octopine catabolism) operon and the occR gene itself. This unusual genetic organization is typical of LysR-type systems and probably allows simultaneous control of both operons. In the proposed study, we shall examine the interaction of OccR with this transcriptional control region. Evidence is presented that OccR binds to this region in the presence or absence of octopine, and that octopine induces conformational changes in Occr and/or its target site. We hypothesize that; i) OccR bends its target site, that octopine incites modulation of this bending, and that these changes result in the induction of transcription, or ii) that octopine-induced conformational changes in OccR itself result in transcriptional activation. The proposed investigation will employ biochemical, molecular biological, and genetic techniques to test these hypotheses.

植物根癌农杆菌的过程是一个很好的研究 这是自然遗传的唯一真实例子。 工程.感染的细菌将它的DNA片段 从肿瘤诱导（Ti）质粒进入宿主植物基因组。 基因 在这个片段上编码的直接肿瘤形成和合成 不寻常的糖和氨基酸称为冠醚， 土壤杆菌特异性碳/氮源。 反过来， 刺激A.根癌基因参与了 摄取和利用，Ti质粒的接合转移，以及 许多其他功能可能参与肿瘤定植。 在章鱼碱型质粒中，这种诱导至少部分由 LysR型转录激活因子OccR，其诱导 这些基因的转录响应于冠瘿碱章鱼碱， 也会自动调节自身的合成 OccR的目标之一 调控是重叠的，差异转录的启动子区域 occ（章鱼碱催化剂）操纵子和occR基因本身之间的关系。 这种不寻常的遗传组织是典型的LysR型系统， 可能允许同时控制两个操纵子。 拟议 在这项研究中，我们将研究OccR与此的相互作用。 转录控制区 有证据表明，OccR结合 在章鱼碱存在或不存在的情况下， 诱导Occr和/或其靶位点的构象变化。 我们 假设：i）OccR弯曲其靶位点，章鱼碱刺激 这种弯曲的调制，这些变化导致 诱导转录，或ii）章鱼碱诱导构象 OccR自身的变化导致转录激活。 的 拟议的调查将采用生物化学、分子生物学， 和基因技术来验证这些假设。