THE LOW CALCIUM RESPONSE AND CYTOTOXIC EFFECT OF PLAGUE

鼠疫的低钙反应和细胞毒性作用

• 批准号: 3132965
• 负责人: Jon D. Goguen
• 金额: $ 10.01万
• 依托单位: UNIV OF MASSACHUSETTS MED SCH WORCESTER
• 依托单位国家: 美国
• 财政年份: 1986
• 资助国家: 美国
• 起止时间: 1986-12-01 至 1988-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3132965
• 关键词: Yersinia pestis; Yersinia pestis disease; bacterial antigens; bacterial cytopathogenic effect; bacterial genetics; bacterial proteins; calcium; electron microscopy; gene expression; genetic manipulation; genetic mapping; genetic transcription; immunoelectrophoresis; laboratory mouse; laboratory rabbit; lysogeny; membrane proteins; mutant; phagocytes; plasmids; radiotracer; temperature; tissue /cell culture; transposon /insertion element; virulence

The low calcium response (LCR) is an essential determinant of virulence in Yersinia pestis, the causative agent of plaque, and in two other human pathogens of the same genus, Y. entercolitica and Y. psuedotuberculosis. LCR is observed as cessation of growth and expression of two novel proteins, the V and W antigens, when cultures in Ca2+ free medium are shifted from 26 degrees C to 37 degrees C. Expression of a group of outer membrane proteins is also associated with the LCR genes. LCR is thought to be triggered by the low free Ca2+ concentrations encountered when Y. pestis enters the intracellular environment and thus, rather than restricting growth, LCR may aid the bacteria in adaptation to intracellular conditions. We have recently observed a cytotoxic effect in Y. pestis specific to the plasmid which encodes LCR. This effect could be the major contribution of LCR to virulence. This project will focus on the cytotoxic effect, V antigen, and regulation of LCR by temperature and by Ca2+ concentration. The genes involved in each of these phenomena will be identified, their function determined and their importance for expression of virulence assessed. These goals will be accomplished by detailed genetic analysis of mutants with specific defects in expression of cytotoxicity or in regulation of LCR, coupled with virulence testing in mice as well as in vitro analysis of phenotypes. For example, regulation by Ca2+ will be investigated with mutants defective in their ability to detect Ca2+. Such mutants still exhibit temperature regulation and express the other features of LCR at 37 degrees C whether or not Ca2+ is present. Additionally, operon fusion strains constructed for analysis of Ca2+ regulation will be used to determine whether or not Ca2+ regulated genes are induced by entry of Y. pestis into animal cells. It is becoming increasingly clear that regulation of virulence genes is an important but poorly studied aspect of pathogenesis. This project will provide one of the first detailed descriptions of the regulation employed by a facultative intracellular pathogen. It may also establish cytotoxicity as the major contribution of LCR to virulence.

低钙反应(LCR)是细菌致病力的重要决定因素 鼠疫耶尔森氏菌，斑块的病原体，在另外两个人类 肠道结肠炎耶尔森氏菌和假结核耶尔森氏菌同属病原菌。 LCR被观察为停止生长和表达两种新的 蛋白质，V和W抗原，当在无钙培养基中培养时 从26摄氏度移动到37摄氏度。 膜蛋白也与LCR基因相关。LCR被认为是 是由鼠疫杆菌遇到的低游离钙浓度触发的 进入细胞内环境，因此，不是限制 生长，LCR可能有助于细菌适应细胞内 条件。我们最近观察到了鼠疫杆菌的一种细胞毒作用。 对编码LCR的质粒具特异性。这种影响可能是主要的 LCR对毒力的贡献。 本项目将重点研究细胞毒作用、V抗原及其调控。 温度和钙离子浓度对LCR的影响。涉及到的基因 这些现象中的每一个都将被识别，它们的功能将被确定，并 评估了它们对毒力表达的重要性。这些目标将是 通过对具有特定缺陷的突变体进行详细的遗传分析完成的 在表达细胞毒性或调节LCR时，与 小鼠毒力测定和表型体外分析。为 例如，将用缺失的突变体研究钙离子的调节。 它们检测钙离子的能力。这样的突变体仍然表现出温度 规定和表达LCR在37摄氏度的其他特征，无论是 不存在钙离子。此外，操纵子融合菌株构建用于 对钙离子调节的分析将用于确定是否有钙离子 受调控的基因是通过鼠疫杆菌进入动物细胞而诱导的。 越来越清楚的是，毒力基因的调控是一种 发病机制的重要但研究甚少的方面。这个项目将 提供所采用的法规的首批详细说明之一 由一种兼性的细胞内病原体引起。它还可以建立 细胞毒性是LCR毒力的主要贡献。