Regulatory network of a conserved polar factor in Sinorhizobium meliloti

描述(由申请人提供)：尽管细菌细胞的尺寸很小，但在亚细胞和分子水平上表现出广泛的动态和程序化组织。过多的专用细胞组件定位并在适当的位置和时间组装，以确保适应不断变化的环境条件，包括入侵其他生物体时遇到的环境条件。这项拟议的项目旨在阐明保守的极性因子的功能网络如何控制阿尔法蛋白细菌Sinorhizobium Meliloti中的多种细胞包膜相关活动，该阿尔法蛋白杆菌感染豆科植物的根形成共生。具体地说，PodJ1蛋白(SMc02230)定位于较新的细胞极点，podJ1基因的缺失干扰了鞭毛的运动、胞外多糖的产生、细胞分裂以及对洗涤剂和渗透胁迫的抗性。微阵列分析表明，podJ1影响129个基因的表达，其中大部分与在podJ1突变体中观察到的表型相关。在没有PodJ1的情况下，表达下调最严重的基因是TACA(SMc04011)，它编码一个保守的转录激活因子。此外，抑制子分析还发现了9个与podJ1基因相互作用的因子。其中两个抑制子(SMc00067和SMc03872)的零突变似乎取消了琥珀多糖的合成，琥珀多糖是一种对共生至关重要的胞外多糖。另一个抑制子编码保守的组氨酸激酶Plec(SMc02369)。这项拟议的研究将(1)研究SMc00067和SMc03872在琥珀多糖生产中的作用，(2)研究必需组氨酸激酶Plec的调节活性，以及()确定TACA转录激活子的功能。将使用多种方法，包括遗传和微阵列分析、表型分析和显微镜，来评估这些因素对苜蓿根结线虫生理的不同方面的影响。研究结果将有助于阐明似乎在阿尔法蛋白细菌组中重复的调控电路，其中包括布鲁氏菌和巴通氏菌等病原体。产生的洞察力将提供对感染期间发生的时空协调的更好理解。

DESCRIPTION (provided by applicant): Despite their minute size, bacterial cells exhibit an extensive degree of dynamic, programmed organization at the subcellular and molecular levels. A plethora of dedicated cellular components localize to and assemble at appropriate positions and times to ensure fitness in ever-changing environmental conditions, including those encountered when intruding into other organisms. The proposed project seeks to clarify how the functional network of a conserved polar factor controls multiple cell envelope-associated activities in the alpha- proteobacterium Sinorhizobium meliloti, which infects the roots of legume plants to form symbiosis. Specifically, the PodJ1 protein (SMc02230) localizes to the newer cell pole and deletion of the podJ1 gene interferes with flagellar motility, exopolysaccharide production, cell division, and resistance against detergents and osmotic stress. Microarray analysis indicated that podJ1 affects the expression of 129 genes, the majority of which correlate with phenotypes observed in the podJ1 mutant. In the absence of PodJ1, the gene whose expression was most severely reduced is tacA (SMc04011), which encodes a conserved transcriptional activator. In addition, suppressor analysis led to the identification of nine factos that interact genetically with podJ1. Null mutations in two of the suppressors (SMc00067 and SMc03872) appear to abolish synthesis of succinoglycan, an exopolysaccharide critical for symbiosis. Another suppressor encodes the conserved histidine kinase PleC (SMc02369). The proposed research will (1) examine the roles of SMc00067 and SMc03872 in succinoglycan production, (2) investigate the regulatory activities of the essential histidine kinase PleC, and () determine the function of the TacA transcriptional activator. How these factors contribute to different aspects of S. meliloti physiology will be assessed using multiple approaches, including genetic and microarray analyses, phenotypic assays, and microscopy. Results from the investigation will help elucidate regulatory circuits that appear to be iterated in the alpha-proteobacteria group, which includes pathogens such as Brucella and Bartonella. The insights generated will provide better understanding of the spatial and temporal coordination that occurs during infection.