Bacillus subtilis stress responses

枯草芽孢杆菌应激反应

基本信息

批准号：
10680374
负责人：
John D Helmann
金额：
$ 79.7万
依托单位：
CORNELL UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2017
资助国家：
美国
起止时间：
2017-06-01 至 2027-05-31
项目状态：
未结题

项目摘要

Project Summary/Abstract Bacteria and humans have a complex relationship: our abundant commensal organisms provide numerous benefits, whereas pathogenic bacteria impose a large burden of morbidity and mortality. The immune system restricts bacterial growth through nutritional immunity, antimicrobial peptides, lytic enzymes, and phagocytic cells. Potential pathogens respond to these threats by the activation of specific adaptive responses, many of which are critical for virulence. We study stress responses in Bacillus subtilis, a model Gram positive bacterium. One project addresses responses to the changing availability of the essential nutrient metal ions zinc, iron, and manganese. The immune system restricts the growth of pathogens by metal sequestration, both in tissues (e.g. by calprotectin) and after phagocytosis. In addition, phagocytic cells kill cells by metal intoxication. We have demonstrated that metal ion homeostasis relies on specific metal-sensing transcription factors that respond to limitation and excess of iron (Fur and PerR), manganese (MntR), and zinc (Zur and CzrA). We will characterize the genes regulated by these transcription factors, their roles in metal homeostasis, and identify the physiological effects that result from both metal ion limitation and intoxication. This work will build upon our recent identification of the major efflux systems for both iron and manganese. The insights from these studies will be directly relevant to the similar stress responses present in human pathogens. The immune system also restricts the growth of pathogens by production of antibacterial peptides and lytic enzymes, both of which affect the integrity of the cell envelope. The cell envelope is also a target for many of our most important antibiotics. In a second project, we have defined several distinct cell envelope stress responses in B. subtilis, with a focus on those regulated by alternative sigma factors. We have identified an array of mutants with alterations in stress response pathways and in key central metabolic pathways that have elevated sensitivity to cell wall antibiotics, including the critically important beta-lactams. In addition, we explore newly discovered antibiotic synergies with possible implications for clinical approaches. Selection of antibiotic resistant suppressors provides a powerful approach for delineating the basis of antibiotic synergies, and the roles of specific stress response pathways. These pathways are central to cell envelope homeostasis generally, in addition to their role in sensing and responding to antibiotic- induced stress, and are implicated in the emergence of antibiotic tolerance and resistance in pathogens.

项目概要/摘要细菌和人类有着复杂的关系：我们丰富的共生生物提供了许多好处，而致病菌却造成了巨大的发病负担死亡。免疫系统通过营养免疫、抗菌作用来限制细菌生长肽、裂解酶和吞噬细胞。潜在的病原体通过以下方式应对这些威胁激活特定的适应性反应，其中许多对于毒力至关重要。我们研究压力枯草芽孢杆菌（一种模型革兰氏阳性细菌）的反应。一个项目解决了以下问题的回应：必需营养金属离子锌、铁和锰的可用性发生变化。免疫系统通过组织中的金属螯合（例如通过钙卫蛋白）来限制病原体的生长以及吞噬作用后。此外，吞噬细胞通过金属中毒杀死细胞。我们有证明金属离子稳态依赖于特定的金属感应转录因子对铁（Fur 和 PerR）、锰（MntR）和锌（Zur 和 CzrA）的限制和过量做出反应。我们将描述这些转录因子调控的基因及其在金属中的作用稳态，并确定金属离子限制和中毒。这项工作将建立在我们最近确定的铁和铁的主要流出系统的基础上和锰。这些研究的见解将与类似的压力直接相关人类病原体中存在的反应。免疫系统还限制病原体的生长通过产生抗菌肽和裂解酶，这两者都会影响细胞的完整性信封。细胞包膜也是许多最重要抗生素的靶标。一秒钟项目中，我们在枯草芽孢杆菌中定义了几种不同的细胞包膜应激反应，重点是那些受替代西格玛因子调节的。我们已经鉴定出一系列具有改变的突变体应激反应途径和对细胞敏感性升高的关键中央代谢途径壁抗生素，包括极其重要的β-内酰胺。此外，我们还新探索发现了抗生素的协同作用，可能对临床方法产生影响。选择抗生素耐药性抑制因子为描述抗生素的基础提供了一种强有力的方法协同作用以及特定应激反应途径的作用。这些途径是细胞的核心除了在感知和响应抗生素方面的作用外，通常还具有包膜稳态诱发应激，并与抗生素耐受性和耐药性的出现有关病原体。