Wu A M, Wu J H, Singh T, Liu J-H, Tsai M-S, Gilboa-Garber N
Glyco-Immunochemistry Research Laboratory, Institute of Molecular and Cellular Biology, College of Medicine, Chang-Gung University, Kwei San, Tao Yuan 333, Taiwan.
Biochimie. 2006 Oct;88(10):1479-92. doi: 10.1016/j.biochi.2006.05.004. Epub 2006 May 24.
Pseudomonas aeruginosa Fuc > Man specific lectin, PA-IIL, is an important microbial agglutinin that might be involved in P. aeruginosa infections in humans. In order to delineate the structures of these lectin receptors, its detailed carbohydrate recognition profile was studied both by microtiter plate biotin/avidin-mediated enzyme-lectin-glycan binding assay (ELLSA) and by inhibition of the lectin-glycan interaction. Among 40 glycans tested for binding, PA-IIL reacted well with all human blood group ABH and Le(a)/Le(b) active glycoproteins (gps), but weakly or not at all with their precursor gps and N-linked gps. Among the sugar ligands tested by the inhibition assay, the Le(a) pentasaccharide lacto-N-fucopentaose II (LNFP II, Galbeta1-3[Fucalpha1-4]GlcNAcbeta1-3Galbeta1-4Glc) was the most potent one, being 10 and 38 times more active than the Le(x) pentasaccharide (LNFP III, Galbeta1-4 [Fucalpha1-3]GlcNAcbeta1-3Galbeta1-4Glc) and sialyl Le(x) (Neu5Acalpha2-3Galbeta1-4[Fucalpha1-3] GlcNAc), respectively. It was 120 times more active than Man, while Gal and GalNAc were inactive. The decreasing order of PA-IIL affinity for the oligosaccharides tested was: Le(a) pentaose > or = sialyl Le(a) tetraose > methyl alphaFuc > Fuc and Fucalpha1-2Gal (H disaccharide)>2'-fucosyllactose (H trisaccharide), Le(x) pentaose, Le(b) hexaose (LNDFH I) and gluco-analogue of Le(y) tetraose (LDFT)>H type I determinant (LNFP I)>Le(x) trisaccharide (Galbeta1-4[Fucalpha1-3]GlcNAc) > sialyl Le(x) trisaccharide >> Man >>> Gal, GalNAc, and Glc (inactive). The results presented here, in accordance with the crystal 3D structural data, imply that the combining site of PA-IIL is a small cavity-type best fitting Fucalpha1- with a specific shallow groove subsite for the remainder part of the Le(a) saccharides, and that polyvalent glycotopes enhance the reactivity. The Fuc > Man Ralstonia solanacearum lectin RSL, which resembles PA-IIL in sugar specificity, differs from it in it's better fit to the B and A followed by H oligosaccharides vs. Fuc, whereas, the second R. solanacearum lectin RS-IIL (the structural homologue of PA-IIL) binds Man > Fuc. These results provide a valuable information on PA-IIL interactions with mammalian glycoforms and the possible spectrum of attachment sites for the homing of this aggressive bacterium onto the target molecules. Such information might be useful for the antiadhesive therapy of P. aeruginosa infections.
铜绿假单胞菌岩藻糖>甘露糖特异性凝集素PA-IIL是一种重要的微生物凝集素，可能参与人类铜绿假单胞菌感染。为了阐明这些凝集素受体的结构，通过微量滴定板生物素/抗生物素蛋白介导的酶-凝集素-聚糖结合测定（ELLSA）以及凝集素-聚糖相互作用的抑制研究了其详细的碳水化合物识别谱。在测试结合的40种聚糖中，PA-IIL与所有人类ABH血型和Le(a)/Le(b)活性糖蛋白（gp）反应良好，但与其前体gp和N-连接的gp反应较弱或根本不反应。在抑制试验测试的糖配体中，Le(a)五糖乳糖-N-岩藻五糖II（LNFP II，Galβ1-3[Fucα1-4]GlcNAcβ1-3Galβ1-4Glc）是最有效的，其活性分别比Le(x)五糖（LNFP III，Galβ1-4 [Fucα1-3]GlcNAcβ1-3Galβ1-4Glc）和唾液酸化Le(x)（Neu5Acα2-3Galβ1-4[Fucα1-3] GlcNAc）高10倍和38倍。它的活性比甘露糖高120倍，而半乳糖和N-乙酰半乳糖胺无活性。PA-IIL对所测试寡糖的亲和力递减顺序为：Le(a)五糖>或=唾液酸化Le(a)四糖>甲基α-岩藻糖>岩藻糖和Fucα1-2Gal（H二糖）>2'-岩藻糖基乳糖（H三糖），Le(x)五糖，Le(b)六糖（LNDFH I）和Le(y)四糖（LDFT）的葡萄糖类似物>H I型决定簇（LNFP I）>Le(x)三糖（Galβ1-4[Fucα1-3]GlcNAc）>唾液酸化Le(x)三糖>>甘露糖>>>半乳糖、N-乙酰半乳糖胺和葡萄糖（无活性）。此处呈现的结果与晶体3D结构数据一致，表明PA-IIL的结合位点是一个小腔型，最适合Fucα1-，并带有一个特定的浅沟亚位点用于Le(a)糖类的其余部分，并且多价糖表位增强了反应性。与PA-IIL糖特异性相似的青枯雷尔氏菌岩藻糖>甘露糖凝集素RSL，在与B和A随后是H寡糖与岩藻糖的匹配度上与其不同，而第二种青枯雷尔氏菌凝集素RS-IIL（PA-IIL的结构同源物）结合甘露糖>岩藻糖。这些结果提供了关于PA-IIL与哺乳动物糖型相互作用以及这种侵袭性细菌归巢到靶分子上可能的附着位点谱的有价值信息。此类信息可能对铜绿假单胞菌感染的抗黏附治疗有用。
