Contributions of Four Cortex Lytic Enzymes to Germination of Bacillus anthracis Spores
Contributions of Four Cortex Lytic Enzymes to Germination of Bacillus anthracis Spores
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DOI：
10.1128/jb.01380-09
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发表时间：
2010-02-01
影响因子：
3.2
通讯作者：
Popham, David L.
中科院分区：
文献类型：
--
作者：
Heffron, Jared D.;Lambert, Emily A.;Popham, David L.
细菌孢子保持休眠状态，对环境压力具有高度抵抗力，直到它们发芽。萌发的完成需要萌发特异性溶解酶（GSLEs）降解孢子皮质肽聚糖。炭疽芽孢杆菌有四个GSLE：CwlJ 1、CwlJ 2、SleB和SleL。在这项研究中，所有四个GSLE在体内的合作行动进行了研究，通过结合框内缺失突变，以产生所有可能的双重，三重和四重GSLE突变株。突变株在孢子萌发和生长过程中的分析结合了光密度损失，集落产生能力和孢子皮层碎片的定量鉴定的观察。单独的裂解转糖基酶SleB可以促进足够的消化，以允许完全的孢子活力，并产生各种小的和大的皮层片段。CwlJ 1也足以允许独立地完成营养物触发的萌发，并且是Ca 2 +-吡啶二羧酸（DPA）触发的萌发中的主要因素，但其酶活性仍然未鉴定，因为其产物大并且不容易从孢子的珠被释放。CwlJ 2对整个皮层消化的贡献最小，但在Ca 2 +-DPA诱导的萌发中起辅助作用。SleL是一种N-乙酰氨基葡萄糖苷酶，在将其他GSLE的大产物水解成小的、快速释放的胞肽中起主要作用。随着这些酶在皮层降解中的作用变得更加清楚，它们将成为刺激B过早萌发的方法的目标。炭疽孢子，大大简化了去污措施。
Bacterial spores remain dormant and highly resistant to environmental stress until they germinate. Completion of germination requires the degradation of spore cortex peptidoglycan by germination-specific lytic enzymes (GSLEs). Bacillus anthracis has four GSLEs: CwlJ1, CwlJ2, SleB, and SleL. In this study, the cooperative action of all four GSLEs in vivo was investigated by combining in-frame deletion mutations to generate all possible double, triple, and quadruple GSLE mutant strains. Analyses of mutant strains during spore germination and outgrowth combined observations of optical density loss, colony-producing ability, and quantitative identification of spore cortex fragments. The lytic transglycosylase SleB alone can facilitate enough digestion to allow full spore viability and generates a variety of small and large cortex fragments. CwlJ1 is also sufficient to allow completion of nutrient-triggered germination independently and is a major factor in Ca2+-dipicolinic acid (DPA)-triggered germination, but its enzymatic activity remains unidentified because its products are large and not readily released from the spore's integuments. CwlJ2 contributes the least to overall cortex digestion but plays a subsidiary role in Ca2+-DPA-induced germination. SleL is an N-acetylglucosaminidase that plays the major role in hydrolyzing the large products of other GSLEs into small, rapidly released muropeptides. As the roles of these enzymes in cortex degradation become clearer, they will be targets for methods to stimulate premature germination of B. anthracis spores, greatly simplifying decontamination measures.