Domestication of a housekeeping transglycosylase for assembly of a Type VI secretion system
Domestication of a housekeeping transglycosylase for assembly of a Type VI secretion system
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DOI：
10.15252/embr.201643206
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发表时间：
2017-01-01
期刊：
影响因子：
7.7
通讯作者：
Cascales, Eric
中科院分区：
文献类型：
--
作者：
Santin, Yoann G.;Cascales, Eric
VI型分泌系统（T6 SS）是一种抗菌武器，其包含通过膜复合物锚定至细胞包膜的可收缩尾。TssJ、TssL和TssM蛋白组装一个1.7-MDa通道复合物，该复合物跨越细胞包膜，包括肽聚糖层。TssJLM复合物的电子显微镜结构显示，它在周质中具有类似于18 nm的直径，其大于肽聚糖孔的尺寸（类似于2 nm），因此质疑T6 SS膜复合物如何穿过肽聚糖层。在这里，我们报告说，MltE管家裂解转糖基酶（LTG）所需的T6 SS组装在肠聚集性大肠杆菌。蛋白质-蛋白质相互作用的研究进一步表明，MltE被募集到TssM的周质结构域。此外，我们表明，TssM显着刺激MltE活性在体外和MltE是所需的后期阶段的T6 SS膜复合物组装。总的来说，我们的数据提供了驯化和激活核心基因组内编码的LTG用于组装分泌系统的第一个例子。
The type VI secretion system (T6SS) is an anti-bacterial weapon comprising a contractile tail anchored to the cell envelope by a membrane complex. The TssJ, TssL, and TssM proteins assemble a 1.7-MDa channel complex that spans the cell envelope, including the peptidoglycan layer. The electron microscopy structure of the TssJLM complex revealed that it has a diameter of similar to 18 nm in the periplasm, which is larger than the size of peptidoglycan pores (similar to 2 nm), hence questioning how the T6SS membrane complex crosses the peptidoglycan layer. Here, we report that the MltE housekeeping lytic transglycosylase (LTG) is required for T6SS assembly in enteroaggregative Escherichia coli. Protein-protein interaction studies further demonstrated that MltE is recruited to the periplasmic domain of TssM. In addition, we show that TssM significantly stimulates MltE activity in vitro and that MltE is required for the late stages of T6SS membrane complex assembly. Collectively, our data provide the first example of domestication and activation of a LTG encoded within the core genome for the assembly of a secretion system.