RUI: Regulation of Nitrogenases in the Cyanobacterium Anabaena Variabilis

丝状蓝细菌是一种独特的微生物，可以 通过植物型光合作用产生能量， 大气氮通过固氮作用。 了固氮作用 光合作用产生的氧气严重抑制; 因此，这两种不相容的代谢过程在空间上是 分居了 光合作用发生在营养细胞中， 固氮作用发生在异形胞中。 异形胞是 终末分化的细胞出现在半规则的 对饥饿的反应 氮气 固氮酶是一种酶复合体，位于 异形胞，这是负责减少大气中的 氮转化为氨。 PI对监管机构感兴趣 控制固氮酶基因表达的信号， 异形胞 她最近发现了一组新的基因， 似乎编码变异鱼腥藻中的第二种固氮酶。 第二种固氮酶在基因上类似于钒- 依赖性固氮酶的特征在于两种 固氮菌 它似乎不是另一个副本， 鱼腥藻的常规固氮酶。 PI建议分析 变异鱼腥藻的两个固氮酶基因， 鉴定重要调控位点和调控基因 在固氮酶表达的发育控制中。

Filamentous cyanobacteria are unique microorganisms which can produce energy by plant type photosynthesis and reduce atmospheric nitrogen by nitrogen fixation. Nitrogen fixation is severely inhibited by the oxygen produced by photosynthesis; hence, these two incompatible metabolic processes are spatially separated. Photosynthesis occurs in vegetative cells and nitrogen fixation occurs in heterocysts. Heterocysts are terminally differentiated cells which arise in a semi-regular pattern in a filament in response to starvation for fixed nitrogen. Nitrogenase is the enzyme complex, localized in heterocysts, that is responsible for the reduction of atmospheric nitrogen to ammonia. The PI is interested in the regulatory signals which control expression of nitrogenase genes in heterocysts. She has recently found a new set of genes that appear to code for a second nitrogenase in Anabaena variabilis. This second nitrogenase is genetically similar to a vanadium- dependent nitrogenase characterized in two species of Azotobacter. It does not appear to be another copy of the conventional nitrogenase of Anabaena. The PI proposes to analyze the two nitrogenase genes of Anabaena variabilis in an attempt to identify regulatory sites and regulatory gene that are important in developmental control of expression of nitrogenases.