CdiA Effectors Use Modular Receptor-Binding Domains To Recognize Target Bacteria.
CdiA Effectors Use Modular Receptor-Binding Domains To Recognize Target Bacteria.
复制标题
DOI：
10.1128/mbio.00290-17
复制
发表时间：
2017-03-28
期刊：
影响因子：
6.4
通讯作者：
Hayes CS
中科院分区：
文献类型：
--
作者：
Ruhe ZC;Nguyen JY;Xiong J;Koskiniemi S;Beck CM;Perkins BR;Low DA;Hayes CS
接触依赖性生长抑制 (CDI) 系统编码 CdiA 效应器，该效应器与邻近细菌上的特定受体结合并传递 C 末端毒素结构域以抑制靶细胞生长。已经鉴定出两类结合不同细胞表面受体的 CdiA 效应子，但受体特异性的分子基础尚不清楚。来自大肠杆菌 EC93 的 BamA 特异性 CdiAEC93 和来自大肠杆菌 536 的 OmpC 特异性 CdiAEC536 的比对表明，受体结合结构域位于两个效应器之间不同的中心区域内。为了支持这一假设，我们发现含有残基 Arg1358 至 Phe1646 的 CdiAEC93 片段与纯化的 BamA 特异性结合。此外，携带 CdiAEC536 相应序列的嵌合 CdiAEC93 具有 OmpC 结合活性，表明该区域决定了受体特异性。对大肠杆菌 CdiA 蛋白的调查揭示了另外两种效应子类别，它们可能识别不同的受体。使用遗传方法，我们将外膜核苷转运蛋白 Tsx 确定为第三类 CdiA 效应子的受体。因此，CDI 系统利用多种外膜蛋白来识别和接合靶细胞。这些结果强调了 CdiA 蛋白的模块化，并表明可以通过基因重组构建新的效应子，以互换不同的受体结合域和毒性有效负载。 CdiB/CdiA 两方分泌蛋白通过多态性毒素结构域的传递介导细菌间竞争。这一过程称为接触依赖性生长抑制 (CDI)，需要 CdiA 效应蛋白与目标细菌表面的特定受体之间存在稳定的相互作用。在这里，我们将受体结合域定位于大肠杆菌 CdiA 的中心区域。 CdiA 蛋白的受体结合域各不相同，大肠杆菌菌株共同编码至少四种不同的效应子类别。此外，我们表明可以通过交换受体结合区域来改变受体特异性，证明了该结构域的模块化。我们提出，新型 CdiA 效应子是通过基因重组自然产生的，以互换不同的受体结合域和毒素有效负载。
Contact-dependent growth inhibition (CDI) systems encode CdiA effectors, which bind to specific receptors on neighboring bacteria and deliver C-terminal toxin domains to suppress target cell growth. Two classes of CdiA effectors that bind distinct cell surface receptors have been identified, but the molecular basis of receptor specificity is not understood. Alignment of BamA-specific CdiAEC93 from Escherichia coli EC93 and OmpC-specific CdiAEC536 from E. coli 536 suggests that the receptor-binding domain resides within a central region that varies between the two effectors. In support of this hypothesis, we find that CdiAEC93 fragments containing residues Arg1358 to Phe1646 bind specifically to purified BamA. Moreover, chimeric CdiAEC93 that carries the corresponding sequence from CdiAEC536 is endowed with OmpC-binding activity, demonstrating that this region dictates receptor specificity. A survey of E. coli CdiA proteins reveals two additional effector classes, which presumably recognize distinct receptors. Using a genetic approach, we identify the outer membrane nucleoside transporter Tsx as the receptor for a third class of CdiA effectors. Thus, CDI systems exploit multiple outer membrane proteins to identify and engage target cells. These results underscore the modularity of CdiA proteins and suggest that novel effectors can be constructed through genetic recombination to interchange different receptor-binding domains and toxic payloads. CdiB/CdiA two-partner secretion proteins mediate interbacterial competition through the delivery of polymorphic toxin domains. This process, known as contact-dependent growth inhibition (CDI), requires stable interactions between the CdiA effector protein and specific receptors on the surface of target bacteria. Here, we localize the receptor-binding domain to the central region of E. coli CdiA. Receptor-binding domains vary between CdiA proteins, and E. coli strains collectively encode at least four distinct effector classes. Further, we show that receptor specificity can be altered by exchanging receptor-binding regions, demonstrating the modularity of this domain. We propose that novel CdiA effectors are naturally generated through genetic recombination to interchange different receptor-binding domains and toxin payloads.