3D structure of EspA filaments from enteropathogenic Escherichia coli
3D structure of EspA filaments from enteropathogenic Escherichia coli
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DOI：
10.1046/j.1365-2958.2003.03555.x
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发表时间：
2003-07-01
影响因子：
3.6
通讯作者：
Frankel, G
中科院分区：
文献类型：
--
作者：
Daniell, SJ;Kocsis, E;Frankel, G
III型分泌系统（TTSS）是由许多致病性革兰氏阴性细菌组装的模块化装置，并且被设计为将蛋白质通过细菌细胞壁转运到真核宿主细胞中。TTSS的保守组分包括跨越内外细菌膜的环堆叠和向外突出的狭窄针状结构。肠致病性E.大肠杆菌的独特之处在于其中一种转运蛋白EspA聚合形成与宿主细胞相互作用的针复合物的延伸。在这项研究中，我们提出了EspA丝的三维结构，以c。通过图像处理从负染色制备物的电子显微照片确定26埃分辨率。该结构包括直径为120埃的螺旋管，其包围直径为25埃的中心通道，效应蛋白可以通过该中心通道转运。亚基排列对应于单起始螺旋，其中28个亚基存在于螺旋的五圈中，并且每个亚基的轴向上升为4.6埃。这是第一次报告的三维结构的丝状延伸的TTSS。
The type III secretion system (TTSS) is a modular apparatus assembled by many pathogenic Gram-negative bacteria and is designed to translocate proteins through the bacterial cell wall into the eukaryotic host cell. The conserved components of the TTSS comprise stacks of rings spanning the inner and outer bacterial membrane and a narrow, needle-like structure projecting outwards. The TTSS of enteropathogenic E. coli is unique in that one of the translocator proteins, EspA, polymerizes to form an extension to the needle complex which interacts with the host cell. In this study we present the 3D structure of EspA filaments to c. 26 Angstrom resolution determined from electron micrographs of negatively stained preparations by image processing. The structure comprises a helical tube with a diameter of 120 Angstrom enclosing a central channel of 25 Angstrom diameter through which effector proteins may be transported. The subunit arrangement corresponds to a one-start helix with 28 subunits present in five turns of the helix and an axial rise of 4.6 Angstrom per subunit. This is the first report of a 3D structure of a filamentous extension to the TTSS.