The Ms6 Mycolyl-Arabinogalactan Esterase LysB is Essential for an Efficient Mycobacteriophage-Induced Lysis.
The Ms6 Mycolyl-Arabinogalactan Esterase LysB is Essential for an Efficient Mycobacteriophage-Induced Lysis.
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DOI：
10.3390/v9110343
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发表时间：
2017-11-17
期刊：
影响因子：
--
通讯作者：
Pimentel M
中科院分区：
文献类型：
--
作者：
Gigante AM;Hampton CM;Dillard RS;Gil F;Catalão MJ;Moniz-Pereira J;Wright ER;Pimentel M
所有dsDNA双链体编码两种参与宿主裂解的蛋白质，分别靶向肽聚糖和细胞质膜的内溶素和孔蛋白。感染革兰氏阴性菌的噬菌体编码额外的蛋白质，即spanins，参与破坏外膜。最近，在分枝杆菌噬菌体基因组中鉴定了位于裂解盒中的基因，其编码具有分枝杆菌酰-阿拉伯半乳聚糖酯酶活性的蛋白质（LysB）。考虑到分枝杆菌噬菌体在其生命周期中遇到的复杂的分枝杆菌细胞包膜，评估这些蛋白在裂解中的作用是有价值的。在目前的工作中，我们构建了一个Ms 6突变体上lysB缺陷，并表明Ms 6 LysB在裂解中具有重要作用。在不存在LysB的情况下，裂解仍然发生，但新合成的噬菌体颗粒被不足地释放到环境中。使用冷冻电子显微镜和断层扫描来记录裂解表型的变化，我们表明，在吸附后150分钟，分支杆菌细胞未完全裂解，噬菌体颗粒保留在细胞内，而感染Ms 6 wt的细胞则完全裂解。我们的研究结果证实，Ms 6 LysB是必要的一个有效的溶解耻垢分枝杆菌，作用，类似于西班牙，在第三步的溶解过程。
All dsDNA phages encode two proteins involved in host lysis, an endolysin and a holin that target the peptidoglycan and cytoplasmic membrane, respectively. Bacteriophages that infect Gram-negative bacteria encode additional proteins, the spanins, involved in disruption of the outer membrane. Recently, a gene located in the lytic cassette was identified in the genomes of mycobacteriophages, which encodes a protein (LysB) with mycolyl-arabinogalactan esterase activity. Taking in consideration the complex mycobacterial cell envelope that mycobacteriophages encounter during their life cycle, it is valuable to evaluate the role of these proteins in lysis. In the present work, we constructed an Ms6 mutant defective on lysB and showed that Ms6 LysB has an important role in lysis. In the absence of LysB, lysis still occurs but the newly synthesized phage particles are deficiently released to the environment. Using cryo-electron microscopy and tomography to register the changes in the lysis phenotype, we show that at 150 min post-adsorption, mycobacteria cells are incompletely lysed and phage particles are retained inside the cell, while cells infected with Ms6wt are completely lysed. Our results confirm that Ms6 LysB is necessary for an efficient lysis of Mycobacterium smegmatis, acting, similarly to spanins, in the third step of the lysis process.
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