TRANSDUCTION OF THE A SIGNAL IN MYXOCOCCUS DEVELOPMENT

粘球菌发育中 A 信号的转导

基本信息

批准号：
2184876
负责人：
HEIDI B KAPLAN
金额：
$ 18.07万
依托单位：
UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
依托单位国家：
美国
项目类别：
财政年份：
1992
资助国家：
美国
起止时间：
1992-05-01 至 1996-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/2184876
关键词：
DNA footprinting Myxococcus bacterial genetics biological signal transduction cell cell interaction developmental genetics gene expression gene mutation genetic mapping genetic regulatory element genetic translation microorganism growth northern blottings nucleic acid sequence open reading frames point mutation regulatory gene starvation

项目摘要

Myxococcus xanthus uses cell-cell interactions to coordinate a developmental program in which cells aggregate to form organized multicellular fruiting bodies and differentiate from rod-shaped cells into ovoid spores. This developmental program is initiated by nutrient limitation at a high cell density. After the removal of nutrients, M. xanthus cells sense their nutritional status and cell density by monitoring the increase in the extracellular A signal concentration, and subsequently activate the A signal transduction pathway. Activation occurs only when the extracellular A signal concentration is within a specific intermediate range. Using a sensitive sensing mechanism, the A signal pathway directs the progression through the early stages of M. xanthus development. Our long term goals are to determine: 1) how the cells sense the extracellular A signal concentration, 2) how this information is transduced, resulting in a change in gene expression and 3) what is the connection between the change in gene expression and the complex behavioral response of multicellular fruiting body formation. To answer these questions we will characterize the regulatory network of the A signal transduction pathway. Several components of this circuitry have been identified, including the extracellular signal, A signal, and a specific response, an increase in expression of a gene, gene4521. A regulatory element has been identified which maps to the sasA (for suppressor of A signal) locus. The sasA locus is required for the progression through early development and differentially regulates the expression of distinct A signal-dependent genes. The focus of this research is to use classical and molecular genetic techniques, combined with protein biochemistry, to fully characterize the sasA locus and its encoded regulatory element. Molecular genetic approaches will be used to analyze the sasA locus structure by defining the physical limits of the locus, analyzing the transcripts, sequencing the region, identifying the open reading frame(s), and construction and characterizing a null mutation. To study the function of the sasA gene product we will determine if the sasA gene product directly or indirectly regulates gene4521 expression. First, the cis-acting regulatory elements controlling gene4521 expression will be determined by deletion analysis. Then, biochemical techniques will be used to test binding of purified sasA gene product to the gene4521 regulatory region. Any binding activity will be characterized in detail. If the sasA gene product appears to indirectly regulate gene4521 expression, biochemical techniques as well as genetic screens will be used to identify possible intermediate regulatory elements. In addition, genetic screens will be developed to identify other components of the A signal transduction pathway, which will likely include a receptor and additional transduction elements.

黄色粘球菌利用细胞与细胞之间的相互作用来协调细胞聚集形成有组织的发育程序多细胞子实体并与杆状细胞分化成卵形孢子。该发育计划由营养素启动高细胞密度的限制。去除营养物质后，M. xanthus 细胞通过以下方式感知其营养状况和细胞密度监测细胞外A信号浓度的增加，以及随后激活A信号转导途径。激活仅当细胞外 A 信号浓度在具体的中间范围。使用灵敏的传感机制，信号通路指导 M 早期阶段的进展。黄花的发育。我们的长期目标是确定：1）细胞如何感知细胞外 A 信号浓度，2) 该信息是怎样的转导，导致基因表达发生变化，3）什么是基因表达变化与复杂性之间的联系多细胞子实体形成的行为反应。来回答这些问题我们将描述 A 的监管网络信号转导途径。该电路的几个组件有已被鉴定，包括细胞外信号、A信号和特异性反应，基因 4521 的表达增加。一个已经确定了映射到 sasA 的监管要素（对于 A 信号的抑制子）位点。 sasA 基因座是必需的通过早期发育进展并差异调节不同A信号依赖性基因的表达。这项研究的重点是利用经典和分子遗传学技术，结合蛋白质生物化学，以充分表征 sasA 基因座及其编码的调控元件。分子遗传学方法将用于通过定义来分析 sasA 位点结构位点的物理限制、分析转录本、测序该区域，识别开放阅读框，以及构建和表征无效突变。研究 sasA 基因的功能我们将确定 sasA 基因产物是否直接或间接调节基因4521的表达。首先，顺式作用将确定控制基因4521表达的调控元件通过删除分析。然后，将使用生化技术来测试纯化的 sasA 基因产物与基因 4521 调控区的结合。任何结合活性都将被详细表征。如果 sasA 基因产品似乎间接调节基因4521的表达，生化技术以及基因筛选将用于识别可能的中间调节元件。此外，基因筛查将开发用于识别 A 信号转导的其他组件途径，可能包括受体和其他转导元件。