Jacob-Dubuisson F, Heuser J, Dodson K, Normark S, Hultgren S
Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO 63110.
EMBO J. 1993 Mar;12(3):837-47. doi: 10.1002/j.1460-2075.1993.tb05724.x.
Uropathogenic Escherichia coli produce heteropolymeric surface fibers called P pili, which present an adhesin at their tip that specifically recognizes globoside receptors on the host uroepithelium. The initial attachment step is thought to be essential for pathogenesis. P pili are composite fibers consisting of a thin tip fibrillum joined end to end to a rigid helical rod. Here we show that the ordered assembly of these structures requires the activity of two proteins that are minor components of the tip fibrillum, PapF and PapK. PapF is required for the correct presentation of the adhesin at the distal end of the tip fibrillum. PapK regulates the length of the tip fibrillum and joins it to the pilus rod. We propose that these subunits function as adaptors, by providing complementary surfaces to different substructures of the pilus and promoting their proper associations. In addition, the conversion of chaperone-subunit complexes into pili depends on PapF and PapK since a papF- papK- double mutation abolishes piliation. We suggest that in addition to the adaptor functions of PapF and PapK, they are also required to initiate the formation of tip fibrillae and pilus rods.
尿路致病性大肠杆菌产生称为P菌毛的杂聚表面纤维，其顶端呈现一种粘附素，该粘附素能特异性识别宿主尿道上皮细胞上的糖苷受体。最初的附着步骤被认为对发病机制至关重要。P菌毛是复合纤维，由细的顶端纤丝首尾相连地连接到刚性螺旋杆组成。我们在此表明，这些结构的有序组装需要顶端纤丝的两种次要成分PapF和PapK的活性。PapF是在顶端纤丝远端正确呈现粘附素所必需的。PapK调节顶端纤丝的长度并将其连接到菌毛杆上。我们提出，这些亚基通过为菌毛的不同亚结构提供互补表面并促进它们的正确结合而作为衔接子发挥作用。此外，伴侣 - 亚基复合物向菌毛的转化取决于PapF和PapK，因为papF - papK - 双突变消除了菌毛形成。我们认为，除了PapF和PapK的衔接子功能外，它们还需要启动顶端纤丝和菌毛杆的形成。
