The outer membrane usher forms a twin-pore secretion complex
The outer membrane usher forms a twin-pore secretion complex
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DOI：
10.1016/j.jmb.2004.10.008
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发表时间：
2004-12-10
影响因子：
5.6
通讯作者：
Thanassi, DG
中科院分区：
文献类型：
--
作者：
Li, HL;Qian, LP;Thanassi, DG
PapC usher是尿路致病性大肠杆菌中毛杆菌组装和分泌所需的外膜蛋白。P . pilus的生物发生是通过总分泌通路的末端分支chaperone/usher通路进行的。周质伴侣-亚基复合物以PapC引子为目标，通过引子将纤维组装和分泌到细胞表面。毛菌在导叶处生物发生的分子细节，以及一般外膜上的蛋白质分泌，目前还不清楚。我们通过凝胶过滤、动态光散射、电子显微镜和图像分析研究了PapC的结构和低聚态。通过将清洁剂纯化后的usher重组到大肠杆菌脂质中，制备了野生型PapC二维晶体和PapC c末端缺失突变体。在洗涤剂溶液和磷脂双分子层中，PapC均形成二聚体。低温电子显微镜显示，usher形成双孔复合物。去除C端结构域没有改变PapC分子的基本形状，但改变了usher的二聚结合，表明C端形成了二聚化界面的一部分。PapC的总分子大小（11 nm）、孔径（2 nm）和双孔结构与线粒体外膜蛋白转位酶Tom40复合物相似。(C) 2004 Elsevier Ltd.版权所有。
The PapC usher is an outer membrane protein required for assembly and secretion of P pili in uropathogenic Escherichia coli. P pilus biogenesis occurs by the chaperone/usher pathway, a terminal branch of the general secretory pathway. Periplasmic chaperone-subunit complexes target to the PapC usher for fiber assembly and secretion through the usher to the cell surface. The molecular details of pilus biogenesis at the usher, and protein secretion across the outer membrane in general, are unclear. We studied the structure and oligomeric state of PapC by gel filtration, dynamic light scattering, and electron microscopy and image analysis. Two-dimensional crystals of wild-type PapC and a C-terminal deletion mutant of PapC were produced by reconstituting detergent purified usher into E. coli lipids. PapC formed a dimer both in detergent solution and in the phospholipid bilayer. Cryo-electron microscopy revealed that the usher forms a twin-pore complex. Removal of the C-terminal domain did not change the basic shape of the PapC molecule, but altered the dimeric association of the usher, suggesting that the C terminus forms part of the dimerization interface. The overall molecular size (11 nm), pore size (2 nm), and twin-pore configuration of PapC resemble that of the Tom40 complex, a mitochondrial outer membrane protein translocase. (C) 2004 Elsevier Ltd. All rights reserved.