The roles of chemotaxis-like signal transduction systems in the differentiation and behavior of motile filaments of the cyanobacterium Nostoc punctiforme

念珠藻属蓝细菌运动的代价是被称为藻殖体的非生长丝状体的短暂分化。藻殖体作为活跃的扩散单位，使生物体能够利用有利的栖息地，或逃离不适宜的栖息地。点状念珠藻的藻殖体具有趋光性和趋化性。punctiforme形成固氮共生体。一个长期的研究目标是在实验中操纵藻殖子的分化和行为，以建立与作物植物的新的固氮关系。N. punctiforme含有5个基因座，编码趋化性样信号转导复合物的蛋白质。在这5个基因座中，一个基因座对藻殖体的分化是必需的，另一个基因座对趋光性是必需的。趋化性样信号转导系统参与细胞分化的调节有优先权，但很少。 将使用多种实验方法来表征趋化性样发育调节基因座（Che 2）和趋光性基因座（Che 4），包括突变分析以确定每个基因座中基因产物的功能要求，DNA微阵列以鉴定Che 2基因座控制下的基因，以及细菌双杂交测定和质谱分析以鉴定信号转导复合物组装中的蛋白质-蛋白质缔合。这些集体实验的结果将提供有关信号转导复合物如何在细胞中以不同方式组织和定位的信息，以及它们如何演变成不同的功能角色，特别是在发育调控中。新兴的数据库将是至关重要的后续操作这些共生蓝藻农业或生物能源应用。该项目将开发可立即提供给科学界的实验工具和材料。一名研究生和一名访问生将接受功能基因组学培训。每年将有两到三名本科生参加短期的、明确的本科生研究项目，接受微生物基因组学、遗传学和生物化学方面的培训。

The price of motility in cyanobacteria of the genus Nostoc is the transient differentiation of non-growing filaments called hormogonia. Hormogonia function as active dispersal units, allowing the organisms to exploit a favorable, or escape an inhospitable, habitat. Hormogonia of Nostoc punctiforme are phototactic, as well as chemotactic to exudates of plant partners, with which N. punctiforme forms a nitrogen-fixing symbiotic association. One long-term research goal is to manipulate hormogonium differentiation and behavior in experiments to establish new nitrogen-fixing associations with crop plants. The genome of N. punctiforme contains five loci of genes that encode proteins of chemotaxis-like signal transduction complexes. Among these five loci, one locus is essential for the differentiation of hormogonia and another for phototaxis. The involvement of a chemotaxis-like signal transduction system in regulation of cellular differentiation has precedence, but is rare. A variety of experimental approaches will be used to characterize the chemotaxis-like developmental regulation locus (Che2) and the phototaxis locus (Che4), including mutational analysis to determine the functional requirement for the gene products in each locus, DNA microarrays to identify genes under control of the Che2 locus, and bacterial two hybrid assays and mass spectrometric analyses to identy protein-protein associations in assembly of the signal transduction complexes. The results of these collective experiments will provide information on how the signal transduction complexes are differently organized and localized in cells, and how they may have evolved into different functional roles, especially in the regulation of development. The emerging database will be essential for subsequent manipulation of these symbiotic cyanobacteria for agricultural or bioenergy applications. The project will develop experimental tools and materials that will be immediately available to the scientific community. A graduate student and visiting student will be trained in functional genomics. Two to three undergraduate students will trained each year in microbial genomics, genetics and biochemistry by their participation in short-term, well-defined, undergraduate research projects.