GENE REARRANGEMENT IN CYANOBACTERIAL HETEROCYST

蓝藻异形体中的基因重排

• 批准号: 3298474
• 负责人: ROBERT HASELKORN
• 金额: $ 6.7万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-07-01 至 1991-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3298474
• 关键词: Cyanophyta; DNA; cell differentiation; developmental genetics; enzyme mechanism; gene expression; gene rearrangement; genetic mapping; genetic recombination; genetic transcription; nitrogen fixation; nucleic acid sequence; operon; plant genetics; plant growth /development; tissue /cell culture

The filamentous cyanobacterium Anabaena differentiates specialized cells called heterocysts at regular intervals along its filaments under conditions of aerobic nitrogen limitation. The heterocyst is an anaerobic factory for nitrogen fixation. During differentiation of a vegetative cell into a heterocyst, genes encoding proteins involved in carbon assimilation are turned off while genes encoding nitrogenase proteins are turned on. We have cloned, physically mapped, and sequenced genes of both classes. The organization of the nif genes found in DNA from vegetative cells of Anabaena differs from the organization found in Klebsiella. However, we have recently found that the nif gene- containing DNA of vegetative cells is rearranged during heterocyst differentiation. One event characterized in some detail is the excision of an 11 Kb element that interrupts the nifD gene in vegetative cells, resulting in the fusion of the nif H, D and K genes into a single operon in heterocysts. A second excision event removes a 55 Kb element that is located on the 5' side of the nifS gene in vegetative cells. This results in the fusion of the nifB gene, from a distant location, to the nifS gene in heterocysts. We propose to purify the enzyme(s) responsible for the nifD recombination, to identify the targets for the recombination enzymes and their reaction mechanism, and to study the regulation of the rearrangement systems during Anabaena heterocyst differentiation. The latter studies will include gene fusions to the xisA gene to determine its transcription control, the preparation and use of antibody to the xisA gene product to follow its fate during heterocyst differentiation, and site-specific inactivation of the xisA gene in Anabaena.

丝状蓝藻鱼腥藻的分化 特殊的细胞被称为杂胞体，沿着它的 在好氧氮限制条件下的细丝。这个 异形胞是一种厌氧固氮工厂。在.期间 营养细胞分化为异形胞，基因 参与碳同化的编码蛋白质被关闭 而编码固氮酶蛋白的基因则处于开启状态。我们有 对两类基因进行克隆、物理定位和测序。 植物DNA中nif基因的组织 鱼腥藻的细胞与 克雷伯氏菌。然而，我们最近发现nif基因- 含有营养细胞DNA的DNA在 异形胞分化。一个事件的特点是 细节是对中断nifD的11 KB元素的删减 基因在营养细胞中，导致nif H，D和 在异形胞中将K基因整合为一个操纵子。第二次切除 事件移除位于5‘端的55 KB元素 营养细胞中的NIFS基因。这导致了 在异形囊中，nifB基因从一个较远的位置转移到nifs基因。 我们建议提纯引起NIFD的酶(S) 重组，以确定重组的目标 酶及其反应机理，并对其进行研究。 鱼腥藻期间重排系统的调节 异形胞分化。后一项研究将包括基因 与XISA基因融合以确定其转录控制， 抗XISA基因产物抗体的制备及应用 在异胞体分化过程中跟踪其命运，并具有部位特异性 鱼腥藻中xisa基因的失活。