Hahn H P
Department of Biological Sciences, University of Alberta, Edmonton, Canada.
Gene. 1997 Jun 11;192(1):99-108. doi: 10.1016/s0378-1119(97)00116-9.
Pseudomonas aeruginosa (Pa) produces several surface-associated adherence factors or adhesins which promote attachment to epithelial cells and contribute to the virulence of this pathogen. Among them, the type-4 pilus accounts for about 90% of the adherence capability of Pa to human lung pneumocyte A549 cells. Furthermore, it is responsible for more than 90% of the virulence in AB.Y/SnJ mice. Pa type-4 pili display a tip-base differentiation with the adherence function located at the tip of the pilus. All Pa pili prototypes characterized so far contain an intrachain disulfide loop (DSL) of 12 to 17 semi-conserved amino acid residues at the C-terminus of pilin. In Pa, this DSL comprises the epithelial cell-binding domain. Despite little sequence homology, DSL-containing peptides of different pilin prototypes seemingly reveal striking structural similarities. Two beta-turns within the loop and the disulfide bridge impose significant structural rigidity on the DSL pilin peptide, suggesting a conformationally conserved binding domain. Insertions of C-terminal pilin peptides with disrupted DSL displayed on the surface of bacterial S-layer mediate the same receptor binding characteristics as pili, indicating that a DSL is not essential in maintaining the functionality of the binding domain. Pa pili bind specifically to the carbohydrate moiety of the glycosphingolipids (GSL) asialo-G(M1) and asialo-G(M2) and, to a much weaker extent, to lactosyl ceramide and ceramide trihexoside. The disaccharide sequence GalNAc beta(1-4)Gal, common in both asialo-G(M1) and asialo-G(M2), likely represents the minimal structural receptor motif recognized by the pili. Pa pili also bind to surface-localized proteins of human epithelial cells and other cell types, suggesting that non-sialylated GSL and (glyco)proteins function as receptors of pili. In addition to the major pilus adhesin, exoenzyme S and, as recent studies indicate, flagella, are further protein adhesins of Pa with GSL receptor binding specificities similar to those of pili.
铜绿假单胞菌（Pa）产生多种与表面相关的黏附因子或黏附素，这些因子促进其与上皮细胞的黏附，并有助于该病原体的致病性。其中，4型菌毛约占Pa对人肺上皮细胞A549细胞黏附能力的90%。此外，它在AB.Y/SnJ小鼠中导致了超过90%的致病性。Pa 4型菌毛呈现出尖端-基部的分化，其黏附功能位于菌毛的尖端。到目前为止，所有已鉴定的Pa菌毛原型在菌毛蛋白的C末端都含有一个由12至17个半保守氨基酸残基组成的链内二硫键环（DSL）。在Pa中，这个DSL包含上皮细胞结合结构域。尽管序列同源性较低，但不同菌毛蛋白原型中含DSL的肽段似乎具有显著的结构相似性。环内的两个β-转角和二硫桥赋予了DSL菌毛蛋白肽显著的结构刚性，表明存在一个构象保守的结合结构域。在细菌S层表面展示的具有破坏的DSL的C末端菌毛蛋白肽的插入介导了与菌毛相同的受体结合特性，这表明DSL对于维持结合结构域的功能并非必不可少。Pa菌毛特异性结合神经节苷脂（GSL）脱唾液酸-G(M1)和脱唾液酸-G(M2)的碳水化合物部分，并且在较弱程度上结合乳糖基神经酰胺和神经酰胺三己糖苷。脱唾液酸-G(M1)和脱唾液酸-G(M2)中常见的二糖序列GalNAcβ(1-4)Gal可能代表了菌毛识别的最小结构受体基序。Pa菌毛还与人上皮细胞和其他细胞类型的表面定位蛋白结合，这表明非唾液酸化的GSL和（糖）蛋白作为菌毛的受体发挥作用。除了主要的菌毛黏附素外，外毒素S以及最近的研究表明，鞭毛是Pa的其他蛋白黏附素，它们具有与菌毛相似的GSL受体结合特异性。
