Genetic Analysis of Nitrogen Fixation in Anabaena Variabilis

固氮作用，即通过固氮酶将大气中的二氮还原为铵，被固定氮抑制，并且因为所有的固氮酶都是氧不稳定的，所以被氧抑制。鱼腥藻属的蓝细菌具有称为异形胞的特化细胞，其功能是固氮。多变鱼腥藻有三种不同的固氮酶：一种依赖钒的固氮酶（vnf）和两种依赖钼的固氮酶，一种在好氧条件下起作用（nif 1），另一种只在严格厌氧条件下起作用（nif 2）。固氮酶基因受到严格的调控;然而，对它们的调控知之甚少。对固氮酶基因调控的认识。variabilis将拓宽我们对原核基因调控机制的理解。固氮酶基因在A. variabilis在许多水平上受到调节，包括氮剥夺、氧张力、金属可用性和异形胞发育。这项研究的目的是确定控制固氮酶基因的调控回路，这些基因在好氧条件下在A.变量其目的是表征固氮酶基因的区域，这些基因对异形胞中的调控表达是必不可少的，并确定负责调控的蛋白质。该项目的更广泛的影响包括研究与本科和研究生教育的整合，包括本科研究课程的开发，这将使课程中的每个学生都能为该研究项目做出实质性贡献。

Nitrogen fixation, the reduction of atmospheric dinitrogen to ammonium by the enzyme nitrogenase, is repressed by fixed nitrogen and, because all nitrogenases are oxygen labile, by oxygen. Cyanobacteria of the genus Anabaena have specialized cells called heterocysts whose function is nitrogen fixation. Anabaena variabilis has three different nitrogenases; a V-dependent nitrogenase (vnf) and two Mo-dependent nitrogenases, one that functions under aerobic conditions (nif1) and one that functions only under strictly anaerobic conditions (nif2). The nitrogenase genes are tightly regulated; however, very little is known about their regulation. An understanding of nitrogenase gene regulation in A. variabilis will broaden our understanding of mechanisms of prokaryotic gene regulation. The nitrogenase genes in A. variabilis are regulated at many levels including nitrogen deprivation, oxygen tension, metal availability, and heterocyst development. The goal of the proposed research is to identify the regulatory circuits that control the nitrogenase genes that function under aerobic conditions in heterocysts of A. variabilis. The aims are to characterize the regions of the nitrogenase genes that are essential for regulated expression in heterocysts and to identify the proteins responsible for regulation. The broader impact of this project includes the integration of research with both undergraduate and graduate education, including the development of an undergraduate research course that will allow each student in the course to make a substantial contribution to this research project.