Kyogashima M, Ginsburg V, Krivan H C
Laboratory of Structural Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892.
Arch Biochem Biophys. 1989 Apr;270(1):391-7. doi: 10.1016/0003-9861(89)90042-8.
Escherichia coli K12, which possess the K99 plasmid and synthesize K99 fimbriae (E. coli K99), cause severe neonatal diarrhea in piglets, calves, and lambs but not in humans. The organism binds specifically and with high affinity to only two glycolipids in piglet intestinal mucosa as demonstrated by overlaying glycolipid chromatograms with 125I-labeled bacteria. These glycolipids, which are N-glycolyl-GM3 (NeuGc alpha 2-3Gal beta 1-4Glc beta 1-1Cer) and N-glycolylsialoparagloboside (NeuGc alpha 2-3Gal beta 1-4GlcNAc beta 1-3Gal beta 1-4Glc beta 1-1Cer), occur at about 13 and 0.3 micrograms per gram wet weight of mucosa, respectively. E. coli K99 grown at 18 degrees C, a temperature at which the K99 fimbriae are not expressed, do not bind to these glycolipids. Of the standard glycolipids tested in solid phase binding assays, E. coli K99 binds with highest affinity to N-glycolylsialoparagloboside, with less affinity to N-glycolyl-GM3, and with very low affinity to N-acetylsialoparagloboside. The bacteria do not bind to GM3 (NeuAc alpha 2-3Gal beta 1-4Glc beta 1-1Cer), GM2 (GalNAc beta 1-4[Neu-Ac alpha 2-3]Gal beta 1-4Glc beta 1-1Cer), GM1 (Gal beta 1-3GalNAc beta 1-4[NeuAc alpha 2-3]Gal beta 1-4Glc beta 1-1Cer), or several other N-acetylsialic acid-containing gangliosides and neutral glycolipids at the levels tested. N-Glycolylsialyl residues are found in the glycoproteins and glycolipids of piglets, calves, and lambs but not in the glycoproteins and glycolipids of humans. Possibly this distribution of sialyl derivatives explains the host range of infection by the organism.
携带K99质粒并合成K99菌毛的大肠杆菌K12（大肠杆菌K99）可导致仔猪、犊牛和羔羊发生严重的新生儿腹泻，但不会导致人类发生腹泻。通过用125I标记的细菌覆盖糖脂色谱图表明，该生物体仅与仔猪肠黏膜中的两种糖脂特异性且高亲和力地结合。这些糖脂分别是N-羟乙酰神经氨酸-GM3（NeuGcα2-3Galβ1-4Glcβ1-1Cer）和N-羟乙酰神经氨酸唾液酸副球蛋白苷（NeuGcα2-3Galβ1-4GlcNAcβ1-3Galβ1-4Glcβ1-1Cer），在每克湿重黏膜中分别约为13微克和0.3微克。在18℃培养的大肠杆菌K99，此温度下不表达K99菌毛，不与这些糖脂结合。在固相结合试验中测试的标准糖脂中，大肠杆菌K99与N-羟乙酰神经氨酸唾液酸副球蛋白苷的亲和力最高，与N-羟乙酰神经氨酸-GM3的亲和力较低，与N-乙酰神经氨酸唾液酸副球蛋白苷的亲和力非常低。该细菌在所测试的水平下不与GM3（NeuAcα2-3Galβ1-4Glcβ1-1Cer）、GM2（GalNAcβ1-4[NeuAcα2-3]Galβ1-4Glcβ1-1Cer）、GM1（Galβ1-3GalNAcβ1-4[NeuAcα2-3]Galβ1-4Glcβ1-1Cer）或其他几种含N-乙酰神经氨酸的神经节苷脂和中性糖脂结合。在仔猪、犊牛和羔羊的糖蛋白和糖脂中发现了N-羟乙酰神经氨酸残基，但在人类的糖蛋白和糖脂中未发现。唾液酸衍生物的这种分布可能解释了该生物体的感染宿主范围。
