Isolation of Early Sporulation Genes

描述(申请人提供)：尽管经过多年的研究，尽管我们对操纵子特定调控的理解取得了很大进展，但我们仍然不清楚细菌如何感知普遍的营养不足，以及它们如何整合它们不断接触到的多种营养信号。这些机制导致细菌具有显著的适应不断变化的环境的能力，并影响细菌与宿主细胞和宿主生物的共生和寄生相互作用。在革兰氏阴性细菌中，亮氨酸反应蛋白(LRP)在调节多种细胞功能的表达方面发挥着重要作用，以应对亮氨酸或某些其他氨基酸的缺乏。在革兰氏阳性细菌中，例如枯草芽孢杆菌，Cody蛋白似乎扮演着类似的角色，尽管Cody和LRP是无关的蛋白质。先前的工作表明，Cody具有对两种不同的关键代谢物GTP和异亮氨酸(或Valine)做出反应的不同寻常的特性。Cody直接或间接抑制数百个基因的表达，其中大多数编码蛋白质，使细胞能够适应有限的营养资源。在与A·J·威尔金森博士的合作下，已经确定了Cody在配体结合和无配体状态下的结构，从而得到了与其配体相互作用使Cody成为有效调节剂的机制的分子模型。Cody还被发现是中枢新陈代谢基因的正向调节因子。因此，Cody规则与其他全局控制的规则以有趣和复杂的方式重叠。大多数Cody同源物在低G+C革兰氏阳性细菌中发现，包括主要病原体。初步结果表明，这些病原菌中的Cody在控制毒力基因表达方面起着重要作用。本研究的目的是确定枯草杆菌Cody的结构和功能是如何相交的，揭示Cody的整体生理作用，评估结构性Cody活性的影响，并通过确定Cody在金黄色葡萄球菌的生长、适应和毒力中的作用来扩展我们对Cody功能的理解。与公共健康相关：科迪蛋白已被发现调节许多细菌基因的表达，包括编码毒素和其他毒力因子的基因。这一建议旨在了解Cody在细菌生命中的生理作用，并揭示Cody抑制或激活基因表达的分子机制。

DESCRIPTION (provided by applicant): Despite many years of research and despite great advances in our understanding of operon-specific regulation, we still do not have a clear view of how bacteria sense general nutrient insufficiency and how they integrate the multiple nutritional signals that they are constantly exposed to. These mechanisms are responsible for the remarkable ability of bacteria to adapt to constantly changing environments and influence the interactions, both symbiotic and parasitic, of bacteria with host cells and host organisms. In gram-negative bacteria, the leucine-responsive protein (Lrp) plays an important role in governing the expression of a wide variety of cellular functions in response to deprivation of leucine or certain other amino acids. In gram-positive bacteria, such as Bacillus subtilis, CodY protein seems to play an analogous role, even though CodY and Lrp are unrelated proteins. Prior work revealed that CodY has the unusual property of responding to two different, critical metabolites, GTP and isoleucine (or valine). CodY represses, directly or indirectly, the expression of hundreds of genes, most of which encode proteins that allow cells to adapt to limited nutritional resources. In collaboration with Dr. A. J. Wilkinson, the structure of CodY has been determined in its ligand-bound and ligand-free states, leading to a molecular model for the mechanism by which interaction with its ligands makes CodY an effective regulator. CodY has also been found to act as a positive regulator of genes of central metabolism. As a result, the CodY regulon overlaps in interesting and complex ways with other globally controlled regulons. Most CodY homologs are found in low G+C gram-positive bacteria, including major pathogens. Preliminary results indicate that CodY in such pathogens contributes in important ways to the control of virulence gene expression. The goals of this proposal are to determine how B. subtilis CodY structure and function intersect, to reveal the overall physiological role of CodY, to assess the effects of constitutive CodY activity, and to extend our understanding of the function of CodY by determining its role in the growth, adaptation and virulence of Staphylococcus aureus. PUBLIC HEALTH RELEVANCE: The CodY protein has been found to regulate the expression of many bacterial genes, including genes that encode toxins and other virulence factors. This proposal seeks to understand the physiological role of CodY in the life of the bacterium and to uncover the molecular mechanism by which CodY represses or activates gene expression.