Formation of oligomeric rings by XcpQ and PilQ, which are involved in protein transport across the outer membrane of Pseudomonas aeruginosa
Formation of oligomeric rings by XcpQ and PilQ, which are involved in protein transport across the outer membrane of Pseudomonas aeruginosa
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DOI：
10.1046/j.1365-2958.1998.00677.x
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发表时间：
1998-01-01
影响因子：
3.6
通讯作者：
Tommassen, J
中科院分区：
文献类型：
--
作者：
Bitter, W;Koster, M;Tommassen, J
铜绿假单胞菌能够跨细胞被膜的两个膜转运蛋白质。这些蛋白质中的许多通过II型分泌途径转运，并在周质中采用其三级构象，这意味着外膜中存在大的转运通道。外膜蛋白，XcpQ，其参与跨铜绿假单胞菌外膜的折叠蛋白的运输，被纯化为高度稳定的同源多聚体。xcpQ的插入和缺失突变显示，XcpQ的C-末端部分足以形成多聚体。然而，在N-末端部分插入接头可以完全干扰复合物的形成。此外，复合物的形成与xcpQ过表达引起的致死率严格相关。XcpQ多聚体的电子显微镜评价揭示了具有95埃的明显中心腔的大的环形结构。纯化的PilQ是参与IV型皮利生物发生的XcpQ的同源物，形成类似的结构，然而，由PilQ形成的表观空腔略小，为53埃。这个空腔的大小可以允许运输完整的IV型皮利。
Pseudomonas aeruginosa is able to translocate proteins across both membranes of the cell envelope. Many of these proteins are transported via the type II secretion pathway and adopt their tertiary conformation in the periplasm, which implies the presence of a large transport channel in the outer membrane. The outer membrane protein, XcpQ, which is involved in transport of folded proteins across the outer membrane of P. aeruginosa, was purified as a highly stable homomultimer. Insertion and deletion mutagenesis of xcpQ revealed that the C-terminal part of XcpQ is sufficient for the formation of the multimer. However, linker insertions in the N-terminal part can disturb complex formation completely. Furthermore, complex formation is strictly correlated with lethality, caused by overexpression of xcpQ. Electron microscopic evaluation of the XcpQ multimers revealed large, ring-shaped structures with an apparent central cavity of 95 Angstrom. Purified PilQ, a homologue of XcpQ involved in the biogenesis of type IV pili, formed similar structures, However, the apparent cavity formed by PilQ was somewhat smaller, 53 Angstrom. The size of this cavity could allow for the transport of intact type IV pili.