Redmond Caroline, Baillie Leslie W J, Hibbs Stephen, Moir Arthur J G, Moir Anne
Defence Science Technology Laboratory, Porton Down, Salisbury, Wiltshire SP4 0JQ, UK.
Biological Defense Research Directorate, Naval Medical Research Center, Silver Spring, MD 20910, USA.
Microbiology (Reading). 2004 Feb;150(Pt 2):355-363. doi: 10.1099/mic.0.26681-0.
Spores of Bacillus anthracis, the causative agent of anthrax, possess an exosporium. As the outer surface layer of these mature spores, the exosporium represents the primary contact surface between the spore and environment/host and is a site of spore antigens. The exosporium was isolated from the endospores of the B. anthracis wild-type Ames strain, from a derivative of the Ames strain cured of plasmid pXO2(-), and from a previously isolated pXO1(-), pXO2(-) doubly cured strain, B. anthracis UM23Cl2. The protein profiles of SDS-PAGE-separated exosporium extracts were similar for all three. This suggests that avirulent variants lacking either or both plasmids are realistic models for studying the exosporium from spores of B. anthracis. A number of loosely adsorbed proteins were identified from amino acid sequences determined by either nanospray-MS/MS or N-terminal sequencing. Salt and detergent washing of the exosporium fragments removed these and revealed proteins that are likely to represent structural/integral exosporium proteins. Seven proteins were identified in washed exosporium: alanine racemase, inosine hydrolase, ExsF, CotY, ExsY, CotB and a novel protein, named ExsK. CotY, ExsY and CotB are homologues of Bacillus subtilis outer spore coat proteins, but ExsF and ExsK are specific to B. anthracis and other members of the Bacillus cereus group.
炭疽病的病原体炭疽芽孢杆菌的孢子具有外孢子囊。作为这些成熟孢子的外层，外孢子囊是孢子与环境/宿主之间的主要接触表面，也是孢子抗原的所在部位。外孢子囊是从炭疽芽孢杆菌野生型Ames菌株的芽孢、质粒pXO2(-)缺失的Ames菌株衍生物以及先前分离的pXO1(-)、pXO2(-)双缺失菌株炭疽芽孢杆菌UM23Cl2中分离得到的。所有这三种菌株经SDS-PAGE分离的外孢子囊提取物的蛋白质谱相似。这表明缺乏一个或两个质粒的无毒变体是研究炭疽芽孢杆菌孢子外孢子囊的理想模型。通过纳米喷雾-MS/MS或N端测序确定的氨基酸序列鉴定出了一些松散吸附的蛋白质。对外孢子囊片段进行盐洗和去污剂洗涤去除了这些蛋白质，并揭示了可能代表外孢子囊结构/整合蛋白的蛋白质。在洗涤后的外孢子囊中鉴定出了七种蛋白质：丙氨酸消旋酶、肌苷水解酶、ExsF、CotY、ExsY、CotB和一种名为ExsK的新蛋白质。CotY、ExsY和CotB是枯草芽孢杆菌外孢子壳蛋白的同源物，但ExsF和ExsK是炭疽芽孢杆菌和蜡样芽孢杆菌属其他成员所特有的。
