TRANSCRIPTIONAL REGULATION IN RHODOBACTER CAPSULATUS

荚膜红杆菌的转录调控

• 批准号: 3466623
• 负责人: Robert G. Kranz
• 金额: $ 12.35万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-02-01 至 1993-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3466623
• 关键词: DNA; Rhodopseudomonas; binding proteins; enzyme mechanism; gene expression; genetic promoter element; genetic transcription; growth media; laboratory rabbit; microorganism genetics; microorganism growth; molecular cloning; mutant; nitrogen fixation; nucleic acid sequence; photosynthetic bacteria; regulatory gene

Rhodobacter capsulatus is a Gram-negative photosynthetic bacterium which possesses the ability to adapt metabolically to a wide range of growth conditions. The capacity to convert from one mode to another is facilitated by complex regulatory systems which respond to changes in culture conditions. The long term goal of the proposed study is to understand these complex regulatory capabilities of R. capsulatus with particular emphasis on the genes for nitrogen fixation. The two major research objectives are: (1) To understand transcriptional regulation of nif genes in response to fixed nitrogen. (2) To determine the mechanism of transcriptional regulation of nif genes and other genes in response to oxygen. It is anticipated that the basic control mechanisms used by R. capsulatus can be added to other organisms with complex regulatory needs. Specific aims include: sequencing and mutagenesis of an ntrA-like gene which codes for a RNA polymerase sigma factor used for nitrogen regulated promoters. 2) Use ntrA-like mutants and mutants in four other nif regulatory genes (called nifR1 through R4) to analyze the regulatory cascades. 3) Testing the hypothesis that various ntrC- like DNA binding proteins (all requiring an ntrA-like sigma factor) modulate activation of different sets of similarly controlled genes. nifR1 from R. capsulatus is required for activation of all the nif genes and has been shown to be homologous to E. coli ntrC. 4) Isolation and characterization of nifR1 through R4- constitutive genes which are locked in their activating states. 5) Sequencing and characterization of nifR5, a gene which complements (i.e. restores) some nifc strains to normal regulation. 6) Since results suggest that DNA supercoiling plays a role in the aerobic repression of nif genes, R. capsulatus strains with varying degrees of DNA topology will be constructed to analyze nif and other anaerobic specific gene transcription. Anaerobic/aerobic gene regulation and complex regulatory cascades are universally employed by both procaryotes and eucaryotes. Basic knowledge of these mechanisms learned in genetically attractive systems such as R. capsulatus can certainly be applied to other bacteria, including anaerobic, aerobic and facultative pathogens. The functional significance of DNA supercoiling on in vivo gene expression is a question of fundamental importance in cells as diverse as bacterial pathogens to human carcinomas.

Rhodobacter capsulatus是一种革兰氏阴性光合作用 具有代谢能力适应A的细菌 广泛的生长条件。 转换的能力 复杂的调节系统促进了一种通往另一种模式 对文化条件的变化做出反应。 长期 拟议的研究的目标是了解这些复杂 R. capsulatus的监管能力特别强调 在氮固定基因上。 两项重大研究 目标是：（1）了解NIF的转录调节 响应固定氮的基因。 （2）确定 NIF基因和其他的转录调控机制 响应氧气的基因。 预计基本 R. capsulatus使用的控制机制可以添加到其他 有复杂调节需求的生物。 具体目的包括： NTRA样基因的测序和诱变，该基因编码为编码 用于氮调节的RNA聚合酶Sigma因子 发起人。 2）在其他四个中使用ntra样突变体和突变体 NIF调节基因（称为NIFR1至R4）以分析 监管级联。 3）检验了各种ntrc-的假设 像DNA结合蛋白（所有需要NTRA样的Sigma因子） 调节不同控制的不同集的激活 基因。 R. capsulatus的Nifr1是激活所有的必需的 NIF基因已被证明与大肠杆菌同源 NTRC。 4）NIFR1通过R4-的分离和表征 锁定在其激活状态的构成基因。 5） NIFR5的测序和表征，一种基因 补充（即恢复）一些NIFC菌株达到正常 规定。 6）由于结果表明DNA超螺旋起作 在NIF基因的有氧抑制作用中的作用 将构建不同程度的DNA拓扑 分析NIF和其他厌氧特异性基因转录。 厌氧/有氧基因调节和复杂调节 cascades均由procaryotes和 桉树。 这些机制的基本知识 诸如capsulatus之类的遗传吸引力的系统肯定可以 应用于其他细菌，包括厌氧，有氧和 辅助病原体。 DNA的功能意义 在体内基因表达上的超螺旋是一个问题 像细菌病原体一样多样化的细胞中的基本重要性 到人类癌。