Cryoelectron-microscopy structure of the enteropathogenic Escherichia coli type III secretion system EspA filament.
Cryoelectron-microscopy structure of the enteropathogenic Escherichia coli type III secretion system EspA filament.
复制标题
肠病性大肠杆菌 III 型分泌系统 EspA 丝的冷冻电子显微镜结构。
DOI：
10.1073/pnas.2022826118
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发表时间：
2021
影响因子：
11.1
通讯作者：
Costa,TiagoRD
中科院分区：
文献类型：
--
作者：
Zheng,Weili;Peña,Alejandro;Ilangovan,Aravindan;Baghshomali,YasamanNaemi;Frankel,Gad;Egelman,EdwardH;Costa,TiagoRD
肠致病性大肠杆菌（EPEC）和肠出血性大肠杆菌（EHEC）利用大分子III型分泌系统（T3SS）将效应蛋白注入真核细胞。该装置跨越内外细菌膜，并包括一个伸入细胞外空间的螺旋针。迄今为止，仅在EPEC和EHEC中观察到，而在其他具有T3SS的致病性革兰氏阴性菌中未发现，是EspA蛋白形成的额外的螺旋丝，形成长长的延伸到针上，介导与真核细胞的附着和效应蛋白通过肠黏液层的运输。在这里，我们以3.4 Å分辨率展示了EPEC的EspA长丝的结构。该结构揭示了EspA丝是一个右旋的1-start螺旋组件，相对于针具有保守的管腔结构，以确保在通往目标细胞的途中无缝运输展开的货物。尽管在序列或结构的水平上几乎没有明显的整体守恒，但这种功能守恒仍然存在。我们还揭示了免疫显性EspA表位的分子细节，现在可以用于表位展示系统的合理设计。
EnteropathogenicEscherichia coli(EPEC) and enterohemorrhagicEscherichia coli(EHEC) utilize a macromolecular type III secretion system (T3SS) to inject effector proteins into eukaryotic cells. This apparatus spans the inner and outer bacterial membranes and includes a helical needle protruding into the extracellular space. Thus far observed only in EPEC and EHEC and not found in other pathogenic Gram-negative bacteria that have a T3SS is an additional helical filament made by the EspA protein that forms a long extension to the needle, mediating both attachment to eukaryotic cells and transport of effector proteins through the intestinal mucus layer. Here, we present the structure of the EspA filament from EPEC at 3.4 Å resolution. The structure reveals that the EspA filament is a right-handed 1-start helical assembly with a conserved lumen architecture with respect to the needle to ensure the seamless transport of unfolded cargos en route to the target cell. This functional conservation is despite the fact that there is little apparent overall conservation at the level of sequence or structure with the needle. We also unveil the molecular details of the immunodominant EspA epitope that can now be exploited for the rational design of epitope display systems.