CdiA promotes receptor-independent intercellular adhesion.
CdiA promotes receptor-independent intercellular adhesion.
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DOI：
10.1111/mmi.13114
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发表时间：
2015-10
影响因子：
3.6
通讯作者：
Hayes CS
中科院分区：
文献类型：
--
作者：
Ruhe ZC;Townsley L;Wallace AB;King A;Van der Woude MW;Low DA;Yildiz FH;Hayes CS
CdiB/CdiA蛋白在称为接触依赖性生长抑制（CDI）的过程中介导细菌间竞争。丝状CdiA外蛋白从CDI+细胞延伸并结合特定受体将毒素传递到易感的目标细菌中。在一些物种中，CDI也参与了自聚集和生物膜的形成，但CDI受体相互作用对这些多细胞行为的贡献尚未得到研究。以大肠杆菌分离物EC93为模型，我们发现cdiA和bamA受体突变体在生物膜形成中存在缺陷，这表明cdiA - bamA介导的细胞-细胞粘附起着重要作用。然而，CdiA也以不依赖于bama的方式促进自动聚集，这表明外显蛋白具有额外的粘附活性。细胞必须表达CdiA才能参与不依赖于CdiA的聚集，这表明黏附可能是由CdiA-CdiA的同型相互作用介导的。依赖于bama和不依赖于bama的相互作用域映射到CdiA丝内不同的区域。因此，CdiA协调了一种独立于其生长抑制活性的集体行为。这种粘附应该使“绿胡子”歧视成为可能，在这种歧视中，基因无关的个体基于一个共同的特征相互合作。这种选择性的社会行为可以为通过水平基因转移获得系统的细菌提供直接的适应性利益。
CdiB/CdiA proteins mediate inter-bacterial competition in a process termed contact-dependent growth inhibition (CDI). Filamentous CdiA exoproteins extend from CDI+ cells and bind specific receptors to deliver toxins into susceptible target bacteria. CDI has also been implicated in auto-aggregation and biofilm formation in several species, but the contribution of CdiA-receptor interactions to these multi-cellular behaviors has not been examined. Using Escherichia coli isolate EC93 as a model, we show that cdiA and bamA receptor mutants are defective in biofilm formation, suggesting a prominent role for CdiA-BamA mediated cell-cell adhesion. However, CdiA also promotes auto-aggregation in a BamA-independent manner, indicating that the exoprotein possesses an additional adhesin activity. Cells must express CdiA in order to participate in BamA-independent aggregates, suggesting that adhesion could be mediated by homotypic CdiA-CdiA interactions. The BamA-dependent and BamA-independent interaction domains map to distinct regions within the CdiA filament. Thus, CdiA orchestrates a collective behavior that is independent of its growth-inhibition activity. This adhesion should enable “greenbeard” discrimination, in which genetically unrelated individuals cooperate with one another based on a single shared trait. This kind-selective social behavior could provide immediate fitness benefits to bacteria that acquire the systems through horizontal gene transfer.