Molecular Cellular and Developmental Biology, University of California, Santa Barbara, CA, USA.
Virulence. 2011 Jul-Aug;2(4):356-9. doi: 10.4161/viru.2.4.16463. Epub 2011 Jul 1.
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 Esherichia coli 536 is a tRNase whereas a CdiA-CT from Dickeya dadantii 3937 has DNase activity. Accordingly, these bacteria contain distinct CdiI proteins, which 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.
接触依赖性生长抑制（CDI）是细菌中鉴定的第一个接触依赖性竞争系统。CDI 是由 CdiA/CdiB 双组分分泌系统介导的，BamA 外膜蛋白作为靶细胞上的 CDI 受体。一种小的免疫蛋白 CdiI 被需要来保护抑制剂细胞免受自身 CDI 系统的影响。我们小组的最新结果表明，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）是多态的，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 tRNase，而来自迪基氏菌 3937 的 CdiA-CT 具有 DNA 酶活性。因此，这些细菌含有不同的 CdiI 蛋白，这些蛋白特异性结合并失活同源的 CdiA-CT。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发挥重要作用的结果。对 CDI 的详细机制理解可以促进针对特定病原体的益生菌和抗菌药物的开发。
