Role of host fucose in cholera toxin action

霍乱毒素是一种由人类病原体霍乱弧菌分泌的AB5毒素。霍乱毒素结合，进入， 并使人类肠道上皮细胞中毒，导致腹泻疾病霍乱。使用一种新陈代谢- 结合在前一批授权期开发的光交联唾液酸类似物，我们表明 霍乱毒素与人结肠表面岩藻糖化糖蛋白直接相互作用 上皮细胞系。此外，宿主细胞表面岩藻糖的显示对霍乱毒素进入的能力至关重要。 并使宿主细胞中毒。在即将到来的授权期内，我们将定义岩藻糖化多糖 霍乱毒素B亚单位(CTB)识别的结构。这些实验的结果将提供 洞察人类霍乱易感性变异的分子基础。此外，信息 在这些实验中获得的将被用来设计能够干扰霍乱毒素的合成分子 可能用于临床，既可作为预防药物，也可用于治疗。我们还将 研究两个葡聚糖结合口袋在CTB上的相对作用-规范的GM1结合位点和 新的岩藻糖化多聚糖结合部位。我们将确定每个部位结合了哪些多糖，这两种多糖是如何结合的 结合部位对CT的作用机制有贡献，以及糖链之间是否存在相互作用 结合部位。最后，我们将探索受体同一性如何影响CTB内化的效率，即 CTB内化的胞内途径，以及CT毒化宿主细胞的能力。这些研究的结果 实验将揭示CT作用的基本机制，并可能提供对分子的新见解 内吞机制的基础。

Cholera toxin is an AB5 toxin secreted by the human pathogen Vibrio cholerae. Cholera toxin binds to, enters, and intoxicates human intestinal epithelial cells, causing the diarrheal disease cholera. Using a metabolically- incorporated photocrosslinking sialic acid analog developed in the prior granting period, we showed that cholera toxin interacts directly with fucosylated glycoproteins displayed on the surface of human colonic epithelial cell lines. Further, host cell surface display of fucose is critical to the ability of cholera toxin to enter and intoxicate host cells. During the upcoming granting period, we will define the fucosylated glycan structures recognized by the B subunit of cholera toxin (CTB). The results of these experiments will provide insight into the molecular basis for human variation in susceptibility to cholera. In addition, information gained in these experiments will be used to design synthetic molecules that can interfere with cholera toxin action and could potentially be used either clinically, either as prophylactics or therapeutics. We will also investigate the relative roles of the two glycan binding pockets on CTB – the canonical GM1 binding site and the novel fucosylated glycan binding site. We will determine which glycans are bound in each site, how the two binding sites contribute to CT mechanism of action, and whether there is any interplay between the glycan binding sites. Finally, we will explore how receptor identity affects the efficiency of CTB internalization, the endocytic pathway for CTB internalization, and the ability of CT to intoxicate host cells. The results of these experiments will reveal fundamental mechanisms of CT action and may provide new insight into the molecular basis of endocytic mechanism.