SPORE PEPTIDOGLYCAN DEGRADATION IN BACILLUS ANTHRACIS

描述（由申请人提供）：炭疽的传染因子是休眠的炭疽芽孢杆菌孢子，感染的建立需要孢子的萌发和生长。孢子皮质肽聚糖壁在萌发过程中的降解是必要的，以允许再水化和恢复孢子核心的代谢。皮层裂解酶在孢子中以无活性形式存在，只有在特定的生发分子存在时才被激活。提出的研究目标是鉴定重要的炭疽芽孢杆菌皮层裂解酶，表征其活性，并了解其激活机制。在炭疽芽孢杆菌休眠和萌发孢子中发现的肽聚糖结构将被确定，以确定在萌发过程中运作的皮层裂解活动。基于序列相似性预测编码皮层裂解酶的基因将被破坏，突变株中萌发裂解活性的变化将被表征。从萌发的炭疽芽孢杆菌孢子中提取和纯化皮层裂解酶。这些蛋白质的酶活性和特性将被确定。对孢子皮质裂解过程的更深入了解将从两个方面提出对抗炭疽感染的可能方法。确定阻断皮层裂解的药物或治疗方法将允许对暴露于孢子的个体进行治疗，以防止感染的建立。确定激活皮层裂解的化学物质或处理方法，导致孢子萌发并使孢子对标准杀菌剂敏感，将使孢子污染部位的净化更容易，并防止人类接触。

DESCRIPTION (provided by applicant): The infectious agent in anthrax is the dormant B. anthracis spore, and establishment of infection requires germination and outgrowth of the spore. Degradation of the spore cortex peptidoglycan wall during germination is necessary to allow rehydration and resumption of metabolism in the spore core. Cortex lytic enzymes are present in an inactive form in the spore and are activated only in the presence of specific germinant molecules. Goals of the proposed studies are identification of the important B. anthracis cortex lytic enzymes, characterization of their activities, and understanding of the mechanisms for their activation. Structures of the peptidoglycan found in B. anthracis dormant and germinating spores will be determined in order to identify cortex lytic activities operating during germination. Genes predicted to encode cortex lytic enzymes, based upon sequence similarities, will be disrupted and changes in germination lytic activities in the mutant strains will be characterized. Cortex lytic enzymes will be extracted and purified from germinating B. anthracis spores. The enzymatic activities and identities of these proteins will be determined. A greater understanding of the process of spore cortex lysis will suggest possible methods for combating anthrax infection on two fronts. Identification of drugs or treatments that block cortex lysis will allow treatment of individuals exposed to spores to prevent establishment of infection. Identification of chemicals or treatments that activate cortex lysis, resulting in germination and rendering the spores susceptible to standard bactericidal agents, will allow easier decontamination of spore-contaminated sites and prevention of human exposure.