Bullitt E, Makowski L
Department of Biophysics, Boston University School of Medicine, Massachusetts 02118-2394.
Nature. 1995 Jan 12;373(6510):164-7. doi: 10.1038/373164a0.
Bacterial adhesion pili are designed to bind specifically and maintain attachment of bacteria to target cells. Uropathogenic P-pili are sufficiently mechanically resilient to resist the cleansing action of urine flow that removes most other bacteria. P-pili are 68 A in diameter and approximately 1 micron long, and are composed of approximately 1,000 copies of the principal structural protein, PapA. They are attached to the outer membrane by a minor structural protein, PapH and are terminated by an approximately 20 A diameter fibrillus composed of PapK, PapE and PapF, which presents the host-binding adhesin PapG. The amino-acid sequences of PapA, PapE, and PapF are similar, with highly conserved C-termini being responsible for binding to PapD, the periplasmic chaperone. Our three-dimensional reconstruction indicates that pili are formed by the tight winding of a much thinner structure. A structural transition allows the pilus to unravel without depolymerizing, producing a thin, extended structure five times the length of the original pilus.
细菌黏附菌毛旨在特异性结合并使细菌维持与靶细胞的附着。尿路致病性P菌毛具有足够的机械弹性，以抵抗尿液流动的冲刷作用，而尿液流动会冲走大多数其他细菌。P菌毛直径为68埃，长度约为1微米，由约1000个主要结构蛋白PapA的拷贝组成。它们通过一种次要结构蛋白PapH附着于外膜，并由由PapK、PapE和PapF组成的直径约20埃的纤维丝终止，该纤维丝呈现宿主结合黏附素PapG。PapA、PapE和PapF的氨基酸序列相似，高度保守的C末端负责与周质伴侣蛋白PapD结合。我们的三维重建表明，菌毛由一种细得多的结构紧密缠绕形成。一种结构转变使菌毛能够解开而不解聚，产生一种比原始菌毛长五倍的细而伸展的结构。
