A Pseudomonas aeruginosa type VI secretion system regulated by CueR facilitates copper acquisition
A Pseudomonas aeruginosa type VI secretion system regulated by CueR facilitates copper acquisition
复制标题
由 CueR 调节的铜绿假单胞菌 VI 型分泌系统有利于铜的获取。
DOI：
10.1371/journal.ppat.1008198
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发表时间：
2019-12-01
期刊：
影响因子：
6.7
通讯作者：
Liang, Haihua
中科院分区：
文献类型：
--
作者：
Han, Yuying;Wang, Tietao;Liang, Haihua
VI型分泌系统（T6SS）广泛分布于革兰氏阴性菌中，其功能已知是将底物转运到真核和原核靶细胞中造成宿主损伤或作为细菌间竞争的武器。铜绿假单胞菌编码三种不同的T6SS簇（H1-， H2-和H3-T6SS）。h1 - t6ss依赖性底物已经被确定并被很好地表征；然而，只有有限的信息可用于H2-和h3 - t6ss，因为相对较少的底物尚未建立。在这里，我们获得了铜绿假单胞菌h2 - t6ss依赖性分泌组，并进一步表征了h2 - t6ss依赖性铜（Cu2+）结合效应物azurin （Azu）。我们的数据表明azu和H2-T6SS均被CueR抑制，并被低浓度Cu2+诱导。我们还确定了azu相互作用的伙伴OprC，一种Cu2+特异性的tonb依赖性外膜转运蛋白。与H2-T6SS基因和azu基因类似，oprC的表达受CueR直接调控，并受低Cu2+诱导。此外，azu - oprc介导的Cu2+转运系统对铜绿假单胞菌细胞的细菌竞争和毒力至关重要。我们的发现为理解t6ss的不同功能以及金属离子在P. aeruginosa细菌-细菌竞争中的作用提供了见解。VI型分泌系统（T6SS）是一种特异性的大分子蛋白输出装置，广泛分布于革兰氏阴性菌中。T6SS在抗菌竞争中发挥重要作用，或向真核和原核细胞递送效应蛋白。在本研究中，我们进行了分泌组分析并鉴定了21种依赖于P. aeruginosa h2 - t6ss的底物。具体来说，我们报道了一个由铜转运体OprC和VI型分泌系统（H2-T6SS）分泌的Cu2+结合蛋白Azu组成的Cu2+清除途径。它们都受转录调控因子CueR的控制。事实上，azu - oprc介导的Cu2+转运系统对铜绿假单胞菌细胞的细菌竞争和毒力至关重要。这些发现说明了铜绿假单胞菌在进化过程中如何利用这种金属系统来适应复杂的环境。
The type VI secretion system (T6SS) is widely distributed in Gram-negative bacteria, whose function is known to translocate substrates to eukaryotic and prokaryotic target cells to cause host damage or as a weapon for interbacterial competition. Pseudomonas aeruginosa encodes three distinct T6SS clusters (H1-, H2-, and H3-T6SS). The H1-T6SS-dependent substrates have been identified and well characterized; however, only limited information is available for the H2- and H3-T6SSs since relatively fewer substrates for them have yet been established. Here, we obtained P. aeruginosa H2-T6SS-dependent secretomes and further characterized the H2-T6SS-dependent copper (Cu2+)-binding effector azurin (Azu). Our data showed that both azu and H2-T6SS were repressed by CueR and were induced by low concentrations of Cu2+. We also identified the Azu-interacting partner OprC, a Cu2+-specific TonB-dependent outer membrane transporter. Similar to H2-T6SS genes and azu, expression of oprC was directly regulated by CueR and was induced by low Cu2+. In addition, the Azu-OprC-mediated Cu2+ transport system is critical for P. aeruginosa cells in bacterial competition and virulence. Our findings provide insights for understanding the diverse functions of T6SSs and the role of metal ions for P. aeruginosa in bacteria-bacteria competition.Author summary The type VI secretion system (T6SS) is a specific macromolecular protein export apparatus, and widely distributed in Gram-negative bacteria. T6SS plays an important role in anti-bacterial competition or delivers effector proteins to both eukaryotic and prokaryotic cells. In the present study, we performed secretomes analysis and identified 21 substrates of P. aeruginosa H2-T6SS-dependent. Specifically, we report a Cu2+-scavenging pathway consisting of a copper transporter, OprC, and a type VI secretion system (H2-T6SS)-secreted Cu2+-binding protein, Azu. Both of them are under control of the transcriptional regulator CueR. Indeed, the Azu-OprC-mediated Cu2+ transport system is critical for P. aeruginosa cells in bacterial competition and virulence. These findings exemplify how P. aeruginosa deploys this metal system to adapt to the complex environment during evolution.