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

蓝藻藻属（Nostoc）运动的代价是不生长的细丝的短暂分化，称为激花。潮虫的功能是作为主动的扩散单位，允许生物体开发一个有利的，或逃离一个不适宜的，栖息地。点孢念珠菌对植物伙伴的分泌物具有趋化性和光敏性，与植物伙伴形成固氮共生关系。一个长期的研究目标是在实验中操纵吸殖菌的分化和行为，以建立与作物植物的新的固氮联系。点状n虫的基因组包含5个基因座，这些基因座编码趋化样信号转导复合物的蛋白质。在这5个基因座中，一个基因座对同源分化至关重要，另一个基因座对趋光性至关重要。趋化样信号转导系统参与细胞分化调控有先例，但很少见。将使用多种实验方法来表征趋化样发育调控位点（Che2）和趋光性位点（Che4），包括突变分析来确定每个位点基因产物的功能需求，DNA微阵列来鉴定Che2位点控制的基因，细菌双杂交测定和质谱分析来鉴定信号转导复合物组装中的蛋白质-蛋白质关联。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不同组织和定位的信息，以及它们如何进化成不同的功能角色，特别是在发育调节中。新兴的数据库将是必不可少的这些共生蓝藻为农业或生物能源应用的后续操作。该项目将开发实验工具和材料，将立即提供给科学界。一名研究生和访问学生将接受功能基因组学方面的培训。每年将有两到三名本科生参加短期、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.