Localization of uroplakin Ia, the urothelial receptor for bacterial adhesin FimH, on the six inner domains of the 16 nm urothelial plaque particle
Localization of uroplakin Ia, the urothelial receptor for bacterial adhesin FimH, on the six inner domains of the 16 nm urothelial plaque particle
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DOI：
10.1006/jmbi.2002.5442
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发表时间：
2002-04-12
影响因子：
5.6
通讯作者：
Kong, XP
中科院分区：
文献类型：
--
作者：
Min, GW;Stolz, M;Kong, XP
尿路致病性大肠杆菌与尿路上皮表面的结合是建立尿路感染的关键初始事件，因为它阻止了细菌通过排尿被清除，并引发细菌入侵和宿主细胞防御。这种结合是由位于细菌1型纤毛顶端的FimH粘附素及其尿路上皮受体uroplakin la （UPIa）介导的。为了将UPIa受体定位在16 nm的颗粒上，这些颗粒形成了不对称单位膜（AUM）的二维晶体，覆盖了90%的顶端尿路上皮表面。采用阴性染色和电子晶体学的方法，构建了一个15 μ m的小鼠三维模型。与之前的低分辨率牛和猪AUM粒子模型类似，小鼠16nm AUM粒子由6个内部和6个外部结构域组成，这些结构域相互连接形成扭曲的带状结构。用0.02- 0.1% （v/v）的Triton X-100处理尿路上皮斑块，使染色剂渗透到膜中，显示出部分尿路上皮跨膜部分，其总直径为14 nm，远远大于之前通过速冻深度染色确定的11 nm值。原生、未固定小鼠和牛尿路上皮斑块的原子力显微镜证实了腔内16nm AUM颗粒的整体结构，该颗粒高出腔膜表面6.5 nm，此外，还显示了一个圆形的、0.5 nm高的细胞质突起，直径类似于14nm。最后，根据存在和不存在重组细菌FimH/FimC复合物的小鼠尿路上皮斑块图像计算的差异图显示，FimH选择性结合到16 nm AUM颗粒的六个内部结构域。这些结果表明，16 nm的AUM颗粒由类似于14 nm直径的跨膜柄锚定，并表明细菌与位于16 nm AUM颗粒六个内部结构域的UPIa结合可能优先触发涉及细菌入侵和宿主细胞防御的跨膜信号。(C) 2002 Elsevier Science Ltd.
The binding of uropathogenic Escherichia coli to the urothelial surface is a critical initial event for establishing urinary tract infection, because it prevents the bacteria from being removed by micturition and it triggers bacterial invasion as well as host cell defense. This binding is mediated by the FimH adhesin located at the tip of the bacterial type 1-fimbrium and its urothelial receptor, uroplakin la (UPIa). To localize the UPIa receptor on the 16 nm particles that form two-dimensional crystals of asymmetric unit membrane (AUM) covering >90 % of the apical urothelial surface, A.. resolution 3-D model of the mouse 16 nm AUM we constructed a 15, particle by negative staining and electron crystallography. Similar to previous lower-resolution models of bovine and pig AUM particles, the mouse16 nm AUM particle consists of six inner and six outer domains that are interconnected to form a twisted ribbon-like structure. Treatment of urothelial plaques with 0.02-0.1 % (v/v) Triton X-100 allowed the stain to penetrate into the membrane, revealing parts of the uroplakin transmembrane moiety with an overall diameter of 14 nm, which was much bigger than the 11 nm value determined earlier by quick-freeze deepetch. Atomic force microscopy of native, unfixed mouse and bovine urothelial plaques confirmed the overall structure of the luminal 16 nm AUM particle that was raised by 6.5 nm above the luminal membrane surface and, in addition, revealed a circular, 0.5 nm high, cytoplasmic protrusion of similar to14 nm diameter. Finally, a difference map calculated from the mouse urothelial plaque images collected in the presence and absence of recombinant bacterial FimH/FimC complex revealed the selective binding of FimH to the six inner domains of the 16 nm AUM particle. These results indicate that the 16 nm AUM particle is anchored by a similar to14 nm diameter transmembrane stalk, and suggest that bacterial binding to UPIa that resides within the six inner domains of the 16 nm AUM particle may preferentially trigger transmembrane signaling involved in bacterial invasion and host cell defense. (C) 2002 Elsevier Science Ltd.