State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Biotechnology, 20 Dongdajie Street, Fengtai District, Beijing, 100071, China.
College of Food Science and Technology, Shanghai Engineering Research Center of Aquatic-Product Processing & Preservation, Shanghai Ocean University, No. 999, Huchenghuan Road, Shanghai, 201306, PR China.
Biochem Biophys Res Commun. 2019 Jun 4;513(3):651-656. doi: 10.1016/j.bbrc.2019.04.056. Epub 2019 Apr 11.
Endospores are important for maintenance of the B. anthracis lifecycle and necessary for its effective spread between hosts. Our experiments with B. anthracis showed that disruption of SpoIIID results in a spore formation defect, as determined by heat resistance assays and microscopic assessment. We further found complete engulfment by the ΔspoIIID mutant strain by membrane morphology staining but no synthesis of the clarity coat and exosporium by transmission electron microscopy. Reduced transcription and expression of small acid-soluble spore protein(sasP-2) and the spore development associated genes (σ, gerE and cotE) in the mother cell were found in the ΔspoIIID strain, suggesting that the spore formation defect in B. anthracis A16R is related to decreased transcription and expression of these genes. Extracellular protease and virulence enhancement in the ΔspoIIID strain may be related to the elevation of metalloproteinases (TasA and Camelysin) levels. Our findings pave the way for further research on the regulation network of sporulation, survival and virulence in these two morphological forms of B. anthracis.
芽孢是炭疽杆菌生命周期维持的重要因素，也是其在宿主间有效传播所必需的。我们的炭疽杆菌实验表明，spoIID 基因的破坏导致芽孢形成缺陷，这可以通过耐热性测定和显微镜评估来确定。我们进一步通过细胞膜形态染色发现，ΔspoIIID 突变菌株完全被吞噬，但透射电子显微镜显示没有清晰涂层和外孢囊的合成。在 ΔspoIIID 菌株中，小酸溶性孢子蛋白（sasP-2）和与孢子发育相关的基因（σ、gerE 和 cotE）的转录和表达减少，表明炭疽杆菌 A16R 的芽孢形成缺陷与这些基因的转录和表达减少有关。ΔspoIIID 菌株中细胞外蛋白酶和毒力增强可能与金属蛋白酶（TasA 和 Camelysin）水平升高有关。我们的研究结果为进一步研究这两种炭疽杆菌形态的孢子形成、生存和毒力的调控网络铺平了道路。
