Synthesis of a selective inhibitor of a fucose binding bacterial lectin from Burkholderia ambifaria
作者:Barbara Richichi、Anne Imberty、Emilie Gillon、Rosa Bosco、Ieva Sutkeviciute、Franck Fieschi、Cristina Nativi
DOI:10.1039/c3ob40520f
日期:——
Burkholderia ambifaria is a bacterium member of the Burkholderia cepacia complex (BCC), a closely related group of Gram-negative bacteria responsible for “cepacia syndrome” in immunocompromised patients. B. ambifaria produces BambL, a fucose-binding lectin that displays fine specificity to human fucosylated epitopes. Here, we report the first example of a synthetic ligand able to selectively bind, in the micromolar range, the pathogen-lectin BambL. The synthetic routes for the preparation of the α conformationally constrained fucoside are described, focusing on a totally diastereoselective inverse electron demand [4 + 2] Diels–Alder reaction. Isothermal titration calorimetry (ITC) demonstrated that this compound binds to the pathogen-associated lectin BambL with an affinity comparable to that of natural fucose-containing oligosaccharides. No binding was observed by LecB, a fucose-binding lectin from Pseudomonas aeruginosa, and the differences in affinity between the two lectins could be rationalized by modeling. Furthermore, SPR analyses showed that this fucomimetic does not bind to the human fucose-binding lectin DC-SIGN, thus supporting the selective binding profile towards B. ambifaria lectin.
安氏伯克霍尔德氏菌(Burkholderia ambifaria)是伯克霍尔德氏头孢菌素复合菌(Burkholderia cepacia complex,BCC)中的一种细菌,这是一类密切相关的革兰氏阴性菌,是免疫力低下患者 "头孢菌素综合征 "的致病菌。B. ambifaria 产生一种岩藻糖结合凝集素 BambL,这种凝集素对人类岩藻糖化表位具有很强的特异性。在这里,我们首次报道了能够在微摩尔范围内选择性结合病原体凝集素 BambL 的合成配体。我们介绍了制备α构象受限岩藻糖苷的合成路线,重点是完全非对映选择性的反电子需求[4 + 2] Diels-Alder反应。等温滴定量热法(ITC)表明,该化合物与病原体相关凝集素 BambL 的结合亲和力与天然含岩藻糖的低聚糖相当。铜绿假单胞菌的岩藻糖结合凝集素 LecB 与该化合物没有结合,而这两种凝集素之间的亲和力差异可以通过建模得到合理解释。此外,SPR 分析表明,这种岩藻糖模拟物不与人类岩藻糖结合凝集素 DC-SIGN 结合,从而支持了对 B. ambifaria 凝集素的选择性结合特征。