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首页> 外文期刊>Infection and immunity >Porcine 987P glycolipid receptors on intestinal brush borders and their cognate bacterial ligands.
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Porcine 987P glycolipid receptors on intestinal brush borders and their cognate bacterial ligands.

机译：肠道刷状边界上的猪987P糖脂受体及其同源细菌配体。

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Certain strains of enterotoxigenic Escherichia coli adhere to piglet intestinal epithelial cells by means of the 987P fimbriae. The 987P fimbrial structure consists of a helical arrangement of three fimbrial proteins, namely, the major subunit FasA and two minor subunits, FasF and FasG. FasG, which is located at the fimbrial tip and at various positions along the fimbriae, mediates 987P binding to glycoprotein receptors. In this study, we isolated and analyzed the structure of piglet glycolipid brush border receptors and characterized their cognate ligands on the 987P fimbriae. Two major glycolipid bands recognized by 987P fimbrial probes in thin-layer chromatography overlay assays were further purified by high-performance thin-layer chromatography and shown to comigrate with control galactosylceramide containing hydroxylated fatty acids and with sulfatide. Their structures were confirmed by fast atom bombardment mass spectrometry, which detected homologous series of ceramide monohexoside and sulfatide with hydroxylated fatty acyl chains ranging from h16:0 to h24:0. Assembled 987P fimbriae, pre- and postassembly dissociated fimbrial subunits, and Fab fragments of specific anti-FasG, -FasF, and -FasA were used to inhibit 987P-mediated bacterial binding to the two identified piglet glycolipids and corresponding isoreceptor controls. Only assembled fimbriae and anti-FasG Fab fragments were significantly able to inhibit bacterial binding to sulfatide, indicating that in addition to glycoproteins, FasG recognizes a specific glycolipid of piglet brush borders. In contrast, only anti-FasA Fab fragments were significantly able to inhibit bacterial binding to galactosylceramide with hydroxylated fatty acids and piglet hydroxylated ceramide monohexoside, indicating that FasA may determine a third type of ligand-receptor interaction in the piglet intestines. Since these bacterial adhesins recognize their respective glycolipid receptors only after being assembled in their final fimbrial quaternary structure, adhesin binding may involve cooperative interactions and the subunits by themselves may have very low binding affinities. Alternatively, conformation-sensitive domains of these subunits present in the assembled fimbriae may be required for glycolipid binding.
机译：某些产肠毒素的大肠埃希菌通过987P菌毛附着在仔猪肠上皮细胞上。 987P纤维结构由三个纤维蛋白（主要亚基FasA和两个次要亚基FasF和FasG）的螺旋排列组成。 FasG位于纤维尖端和沿纤维膜的各个位置，介导987P与糖蛋白受体的结合。在这项研究中，我们分离并分析了仔猪糖脂刷状边界受体的结构，并表征了它们在987P菌毛上的同源配体。在薄层色谱叠加分析中，由987P纤维探针识别的两个主要糖脂条带通过高效薄层色谱进一步纯化，并显示出与含羟基脂肪酸的半乳糖基神经酰胺和硫酸脂的迁移率。通过快速原子轰击质谱法确认了它们的结构，该质谱法检测到具有从h16：0到h24：0的羟基化脂肪酰基链的神经酰胺单己糖苷和硫酸脂的同源系列。组装的987P菌毛，组装前和组装后解离的纤维亚基以及特异性抗FasG，-FasF和-FasA的Fab片段可用于抑制987P介导的细菌与两个已鉴定的仔猪糖脂和相应的同型异体受体对照的结合。只有组装的菌毛和抗FasG Fab片段才能显着抑制细菌与硫化物的结合，这表明除了糖蛋白以外，FasG还可以识别仔猪刷缘的特定糖脂。相比之下，只有抗FasA Fab片段才能显着抑制细菌与羟基脂肪酸和仔猪羟基化神经酰胺单己糖苷的半乳糖基神经酰胺结合，这表明FasA可能决定了仔猪肠道中第三种类型的配体-受体相互作用。由于这些细菌粘附素仅在组装成其最终的纤维四级结构后才识别其各自的糖脂受体，因此粘附素结合可能涉及协同相互作用，而亚基本身可能具有非常低的结合亲和力。或者，糖脂结合可能需要组装菌毛中存在的这些亚基的构象敏感域。

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