Pdl1 is a putative lipase that enhances Photorhabdus toxin complex secretion.
Pdl1 is a putative lipase that enhances Photorhabdus toxin complex secretion.
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DOI：
10.1371/journal.ppat.1002692
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发表时间：
2012
期刊：
影响因子：
6.7
通讯作者：
Waterfield NR
中科院分区：
文献类型：
--
作者：
Yang G;Hernández-Rodríguez CS;Beeton ML;Wilkinson P;Ffrench-Constant RH;Waterfield NR
毒素复合物（TC）是一种大型多亚基毒素，最初在昆虫病原体Photorhabdus和Xabrihabdus中发现，但现在在一系列病原体中发现，包括人类的病原体。这些复合物包括三个蛋白质亚基，A、B和C，它们在黄杆菌毒素中以4∶1∶1的化学计量比存在。一些三氯甲烷已被证明对昆虫具有口服毒性，并有可能被开发为一种害虫控制技术。在这三个大的组分蛋白中缺乏可识别的信号序列阻碍了对它们的分泌模式的理解。尽管如此，我们已经表明发光杆菌（Pl）Tcd复合物已被证明与细菌的表面相关联，尽管一些菌株也可以将其释放到周围环境中。Pl中大量的tc基因同源物使得出口过程的研究变得困难，因此我们已经开发并验证了异源大肠杆菌表达模型来研究这些重要毒素的释放。除了这个模型之外，我们还使用了将高水平的Tcd释放到上清液中的菌株和将毒素保留在其表面上的菌株之间的比较基因组学，以确定负责增强这些毒素的分泌和释放的蛋白质。这种蛋白质是一种推定的脂肪酶（Pdl1），由一个小的紧密连接的拮抗剂蛋白（Orf53）调节。这些在其他细菌中的同源物的鉴定，与其他毒力因子操纵子，如VI型分泌系统，表明这些基因代表了一个通用的和广泛的机制，提高革兰氏阴性病原体中的毒素释放。昆虫的细菌病原体部署一系列毒素来对抗先天免疫系统并杀死宿主。人们对开发这些毒素作为作物保护战略的候选物有很大的兴趣。迄今为止，表达苏云金芽孢杆菌Cry毒素的转基因作物已被用于抵抗害虫的捕食。为了最大限度地减少昆虫抗性发展的风险，目前的作物生物技术研究包括设计表达具有不同作用模式的毒素的新转基因植物。毒素复合物（TC）基因家族首先在昆虫病原体Photorhabdus中被发现，作为一种替代方法，它受到了人们的关注。目前还不清楚光杆状菌是如何调节、组装和分泌如此大的毒素复合物的。我们已经确定了一种小的脂肪酶蛋白，Pdl 1，它可以增强分泌，并导致毒素复合物从细菌表面释放。这具有更广泛的意义，因为TC毒素同系物也在一系列人类病原体中发现，例如耶尔森氏菌，其中它们与人类毒力有关。此外，还发现pdl的同源物与其他毒力基因座如弧菌的VI型系统紧密连锁。我们推测这种Pdl介导的分泌增强系统是革兰氏阴性细菌病原体使用的广泛且重要的机制。
The Toxin Complex (TC) is a large multi-subunit toxin first characterized in the insect pathogens Photorhabdus and Xenorhabdus, but now seen in a range of pathogens, including those of humans. These complexes comprise three protein subunits, A, B and C which in the Xenorhabdus toxin are found in a 4∶1∶1 stoichiometry. Some TCs have been demonstrated to exhibit oral toxicity to insects and have the potential to be developed as a pest control technology. The lack of recognisable signal sequences in the three large component proteins hinders an understanding of their mode of secretion. Nevertheless, we have shown the Photorhabdus luminescens (Pl) Tcd complex has been shown to associate with the bacteria's surface, although some strains can also release it into the surrounding milieu. The large number of tc gene homologues in Pl make study of the export process difficult and as such we have developed and validated a heterologous Escherichia coli expression model to study the release of these important toxins. In addition to this model, we have used comparative genomics between a strain that releases high levels of Tcd into the supernatant and one that retains the toxin on its surface, to identify a protein responsible for enhancing secretion and release of these toxins. This protein is a putative lipase (Pdl1) which is regulated by a small tightly linked antagonist protein (Orf53). The identification of homologues of these in other bacteria, linked to other virulence factor operons, such as type VI secretion systems, suggests that these genes represent a general and widespread mechanism for enhancing toxin release in Gram negative pathogens. Bacterial pathogens of insects deploy a range of toxins to combat the innate immune system and kill the host. There is significant interest in developing these toxins as candidates for crop protection strategies. To date, transgenic crops expressing Bacillus thuringiensis Cry toxins have been used to resist predation by pests. In order to minimize the risk of insect resistance development, current research in crop biotechnology comprises the design of new transgenic plants expressing toxins with different modes of action. The Toxin Complex (TC) gene family first identified in the insect pathogen Photorhabdus has received interest as an alternative. It remains obscure how Photorhabdus regulates, assembles, and secretes such a large toxin complex. We have identified a small lipase protein, Pdl1, which enhances secretion and leads to the release of the Toxin complex off the bacterial surface. This is of wider significance because TC toxin homologues are also found in a range of human pathogens, such as Yersinia in which they have been implicated in human virulence. Furthermore homologues of pdl are also seen tightly linked to other virulence loci such as the type VI systems of Vibrio. We speculate that this Pdl mediated secretion enhancement system is a widespread and important mechanism used by Gram negative bacterial pathogens.
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DOI：
10.1073/pnas.102068099
发表时间：
2002-08-06
影响因子：
11.1
作者：
Daborn, PJ;Waterfield, N;Ffrench-Constant, RH
通讯作者：
Ffrench-Constant, RH
影响因子：
3.4
作者：
Erickson, David L.;Waterfield, Nicholas R.;Hinnebusch, B. Joseph
通讯作者：
Hinnebusch, B. Joseph
影响因子：
4.4
作者：
Sergeant, M;Jarrett, P;Morgan, JAW
通讯作者：
Morgan, JAW
影响因子：
5.6
作者：
Lee, Sarah C.;Stoilova-Mcphie, Svetla;Morgan, J. Alun W.
通讯作者：
Morgan, J. Alun W.
影响因子：
3.6
作者：
Cowles, CE;Goodrich-Blair, H
通讯作者：
Goodrich-Blair, H