The ESX-5 associated eccB-EccC locus is essential for Mycobacterium tuberculosis viability.
The ESX-5 associated eccB-EccC locus is essential for Mycobacterium tuberculosis viability.
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DOI：
10.1371/journal.pone.0052059
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Esin S
中科院分区：
文献类型：
--
作者：
Di Luca M;Bottai D;Batoni G;Orgeur M;Aulicino A;Counoupas C;Campa M;Brosch R;Esin S
新近报道的结核分枝杆菌ESX-5分泌系统对PPE蛋白的分泌、细胞壁的稳定性和毒力具有重要影响，是宿主-病原菌相互作用的重要调节因子之一。虽然已经定义了ESX-5分泌机制的各种组件，但其他ESX-5核心组件仍有待确定。在这项研究中，我们重点研究了EccB5和EccC5，一种跨膜蛋白(EccB5)和一种膜结合ATPase(EccC5)，这两种蛋白都被预测为结核分枝杆菌ESX-5膜相关复合体的构建块。体外表达研究表明，EccB5和EccC5编码基因构成操纵子。这个操纵子的表达对结核分枝杆菌是必不可少的，因为只有在第二个eccB5-eccC5基因的功能拷贝整合到结核分枝杆菌染色体之后，ESX-5基因座的eccB5-eccC5基因组片段才有可能被删除。两株结核分枝杆菌条件突变株(MtbPptreccB5和MtbPptreccC5)的特性表明，eccB5-eccC5操纵子和eccC5基因分别在厌氢四环素阻遏启动子的控制下表达，证实eccB5-eccC5基因的抑制在体外和THP-1人巨噬细胞系中都不利于结核分枝杆菌的生长。此外，对MtbPptreccB5-eccC5和MtbPptreccC5菌株的分泌组分析表明，EccB5和EccC5都是分泌ESX-5特异性底物所必需的，从而证实它们确实是ESX-5分泌机制的组成部分。综上所述，这些发现证明了完整和有效的ESX-5系统对结核分枝杆菌生存能力的重要性，从而为替代抗分枝杆菌控制策略开辟了新的有趣的选择。
The recently described ESX-5 secretion system of Mycobacterium tuberculosis is one of the most important modulators of host-pathogen interactions due to its crucial impact on PPE protein secretion, cell wall stability and virulence. Although various components of the ESX-5 secretion machinery have been defined, other ESX-5 core components still remain to be characterized. In this study, we focused on EccB5 and EccC5, a transmembrane protein (EccB5) and a membrane-bound ATPase (EccC5), both predicted to be building blocks of the M. tuberculosis ESX-5 membrane-associated complex. In vitro expression studies demonstrated that EccB5 and EccC5 encoding genes constitute an operon. The expression of this operon is essential for M. tuberculosis, since the deletion of the eccB5-eccC5 genomic segment at the ESX-5 locus is possible only after the integration of a second functional copy of eccB5-eccC5 genes into the M. tuberculosis chromosome. The characterization of two M. tuberculosis conditional mutant strains (MtbPptreccB5 and MtbPptreccC5), in which the eccB5-eccC5 operon or the eccC5 gene, respectively, were expressed under the control of an anhydrotetracycline-repressible promoter, confirmed that the repression of eccB5-eccC5 genes is detrimental for growth of M. tuberculosis both in vitro and in THP-1 human macrophage cell line. Moreover, analysis of the secretome of MtbPptreccB5-eccC5 and MtbPptreccC5 strains revealed that both EccB5 and EccC5 are required for secretion of ESX-5 specific substrates, thus confirming that they are indeed components of the ESX-5 secretion machinery. Taken together these findings demonstrate the importance of an intact and functional ESX-5 system for viability of M. tuberculosis, thus opening new interesting options for alternative antimycobacterial control strategies.
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影响因子：
3.6
作者：
Coros, Abbie;Callahan, Brian;Derbyshire, Keith M.
通讯作者：
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DOI：
10.1073/pnas.94.20.10955
发表时间：
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影响因子：
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发表时间：
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影响因子：
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作者：
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作者：
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