Toxin on a stick Modular CDI toxin delivery systems play roles in bacterial competition
Toxin on a stick Modular CDI toxin delivery systems play roles in bacterial competition
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DOI：
10.4161/viru.2.4.16463
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发表时间：
2011-07-01
期刊：
影响因子：
5.2
通讯作者：
Low, David A.
中科院分区：
文献类型：
--
作者：
Aoki, Stephanie K.;Poole, Stephen J.;Low, David A.
接触依赖性生长抑制（CDI）是在细菌中发现的首个接触依赖性竞争系统。CDI由CdiA/CdiB双组分分泌系统介导，BamA外膜蛋白作为靶细胞上的CDI受体。一种小的免疫蛋白CdiI是保护抑制性细胞免受自身CDI系统影响所必需的。我们小组最近的研究结果表明，CDI系统存在于许多重要的革兰氏阴性植物和动物病原体中。CdiA的C末端区域（CdiA - CT）具有多态性，并含有生长抑制活性。来自尿路致病性大肠杆菌536的CdiA - CT是一种tRNA酶，而来自Dickeya dadantii 3937的CdiA - CT具有DNA酶活性。因此，这些细菌含有不同的CdiI蛋白，它们能特异性结合并使同源的CdiA - CT失活。值得注意的是，CdiA - CT是模块化的：一个CdiA“棒”可以传递不同的CdiA - CT毒素。我们讨论了这些发现以及表明CDI在自然界中菌株内细菌竞争中起重要作用的结果。对CDI详细的机制理解可以促进针对特定病原体的益生菌和抗菌剂的开发。
Contact-dependent growth inhibition (CDI) is the first contact-dependent competition system identified in bacteria. CDI is mediated by the CdiA/CdiB two-partner secretion system, and the BamA outer membrane protein serves as the CDI receptor on target cells. A small immunity protein, CdiI, is required to protect inhibitor cells from their own CDI system. Recent results from our group show that CDI systems are present in a number of important gram-negative plant and animal pathogens. The C-terminal region of CdiA (CdiA-CT) is polymorphic and contains growth inhibitory activity. The CdiA-CT from uropathogenic Escherichia coli 536 is a tRNase whereas a CdiA-CT from Dickeya dadantii 3937 has DNase activity. Accordingly, these bacteria contain distinct CdiI proteins that specifically bind and inactivate cognate CdiA-CT. Remarkably, CdiA-CTs are modular: one CdiA "stick" can deliver different CdiA-CT toxins. We discuss these findings as well as results showing that CDI plays an important role in intra-strain bacterial competition in the natural world. A detailed mechanistic understanding of CDI could facilitate development of probiotics and antimicrobials that target specific pathogens.