GENE REARRANGEMENT IN CYANOBACTERIAL HETEROCYST

蓝藻异形体中的基因重排

• 批准号: 3298473
• 负责人: ROBERT HASELKORN
• 金额: $ 18.63万
• 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 1996-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3298473
• 关键词: Cyanophyta; DNA; Escherichia coli; cell differentiation; developmental genetics; enzyme mechanism; fusion gene; gene deletion mutation; gene expression; gene rearrangement; genetic mapping; genetic recombination; immunocytochemistry; microorganism conjugation; microorganism culture; mutant; nitrogen fixation; nucleic acid repetitive sequence; operon; plant genetics; plant growth /development; radiotracer; reporter genes; site directed mutagenesis; transposon /insertion element

Anabaena 7120 is a filamentous cyanobacterium that differentiates specialized N2-fixing cells called heterocysts along its filaments in response to limiting levels of fixed nitrogen in its environment. Heterocysts form in a simple pattern that is maintained during diazotrophic growth. The DNA in vegetative cells of Anabaena contains two elements that interrupt the coding regions of genes required for nitrogen fixation. During differentiation of heterocysts, these interrupting elements are excised by site-specific recombination between repeated sequences at the ends of the elements. The overall goal of this program is an understanding of the regulation of heterocyst differentiation, and the elucidation in molecular terms of the mechanism of these excision events in the context of heterocyst development. The availability of a system for the isolation of genes required for the development of functional heterocysts has made possible a more comprehensive study of the regulatory circuits that control differentiation and the developmental pattern in Anabaena. This work is relevant to both the programmed recombination events that occur in immuno-globulin-producing cells and to the recombinations between directly repeated sequences in humans that lead to deletion of essential genes. Elucidation of the mechanism of pattern formation and maintenance may also have relevance to the problem of spatial control of tissue differentiation in higher eukaryotes, especially as this relates to abnormalities in human fetal development. The projects to be pursued include the isolation of mutants that fail to differentiate heterocysts normally or that fail to rearrange their nif DNA; the classification and complementation of such mutants; analysis of the genes isolated by complementation by DNA sequencing, protein expression in E. coli, and cellular localization by immunocytochemistry; the isolation and characterization of new developmental mutants that arise in populations of cells engineered to overproduce heterocysts; the regulation of the gene encoding excisase studied by using gene fusions and the selection of non- expressing mutants; and the determination of the role in heterocyst development of two newly-isolated genes that affect pattern formation.

鱼腥藻7120是一种丝状蓝藻， 一种特殊的固氮细胞，称为异形胞，沿着它的细丝， 对环境中固定氮的限制水平的反应。 异形胞以一种简单的模式形成， 增长 鱼腥藻营养细胞中的DNA含有两种成分， 中断固氮所需基因的编码区。 在异形胞的分化过程中，这些中断元素是 通过重复序列之间的位点特异性重组切除 元素的末端。 该计划的总体目标是了解 异形胞分化，并在分子方面的说明， 在异形胞背景下这些切除事件的机制 发展 基因分离系统的可用性 所需的发展功能异形囊已经成为可能， 更全面地研究控制神经元的调节回路， 鱼腥藻的分化和发育模式。 这项工作与编程重组事件有关， 发生在免疫球蛋白产生细胞中， 直接重复的序列，导致人类的基本 基因. 模式形成和维持机制的阐明 也可能与组织的空间控制问题有关 在高等真核生物中的分化，特别是因为这涉及到 人类胎儿发育的异常。 将要进行的项目包括分离那些不能 正常分化异形胞或不能重排其nif DNA; 这类突变体的分类和互补; 通过DNA测序互补分离的基因， E.大肠杆菌，并通过免疫细胞化学进行细胞定位;分离 以及对种群中出现的新的发育突变体的表征 细胞工程过量生产异形胞;基因的调节 通过使用基因融合和选择非- 表达突变体;以及确定在异形胞中的作用 两个新分离的基因影响模式的形成。