A DNA Conformation-Dependent Genetic Switch in Halobacterium

盐杆菌中 DNA 构象依赖性遗传开关

• 批准号: 9604443
• 负责人: Shiladitya DasSarma
• 金额: $ 24.4万
• 依托单位: University of Massachusetts Amherst
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-02-01 至 2001-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9604443&HistoricalAwards=false
• 关键词: DNA; Conformation; Dependent; Genetic; Switch

9604443 DasSarma This research tests the hypothesis that specific regions of the genome of Halobacterium halobium adopt supercoil density-dependent Z-DNA conformations that function as regulatory switches for the control of gene expression. Halobacterium halobium is an extremely halophilic Archaea in which the left-handed Z-DNA conformation is favored by a highly negative DNA supercoiling density, a high G+C content including alternating CG sequences, and a high cytoplasmic salt concentration (5M). A combination of mutagenic and biochemical analysis will determine if expression of the bop gene encoding the H. halobium purple membrane protein is controlled by B-to-Z DNA conformation-dependent switch at a potential Z-DNA sequence located 23 base pairs upstream from the bop gene transcription start site. Preliminary evidence indicates that bop gene transcription is induced under conditions of highly negative DNA supercoiling, and reduced when supercoiling is relieved by inhibition of DNA gyrase. Therefore, the DNA gyrase inhibitor novobiocin will be used to determine the role of DNA supercoiling in mediating DNA conformational changes and bop transcription, including the development of an in vitro transcription system for studying the effects of DNA supercoiling on transcription. %%% This research will evaluate the role of DNA conformation and conditions that affect DNA conformation in the regulation of gene expression in Halobacterium halobium, a Archaea bacteria that exists under conditions of extremely high salt concentration. ***

9604443 DasSarma 这项研究测试了这样的假设：盐杆菌基因组的特定区域采用超螺旋密度依赖性 Z-DNA 构象，充当控制基因表达的调节开关。 盐杆菌是一种极其嗜盐的古细菌，其左手 Z-DNA 构象受高负 DNA 超螺旋密度、高 G+C 含量（包括交替 CG 序列）和高细胞质盐浓度 (5M) 的影响。 诱变和生化分析相结合，将确定编码 H. halobium 紫膜蛋白的 bop 基因的表达是否受位于 bop 基因转录起始位点上游 23 个碱基对的潜在 Z-DNA 序列处的 B-to-Z DNA 构象依赖性开关控制。 初步证据表明，bop 基因转录在高度负 DNA 超螺旋条件下被诱导，并在通过抑制 DNA 旋转酶缓解超螺旋时减少。 因此，DNA旋转酶抑制剂新生霉素将用于确定DNA超螺旋在介导DNA构象变化和bop转录中的作用，包括开发体外转录系统来研究DNA超螺旋对转录的影响。 %%% 这项研究将评估 DNA 构象和影响 DNA 构象的条件在盐杆菌基因表达调节中的作用，盐杆菌是一种存在于极高盐浓度条件下的古细菌。 ***