Wren B W, Russell R R, Tabaqchali S
Department of Medical Microbiology, St. Bartholomew's Hospital Medical College, West Smithfield, London, United Kingdom.
Infect Immun. 1991 Sep;59(9):3151-5. doi: 10.1128/iai.59.9.3151-3155.1991.
A 10-amino-acid repeating sequence of the hemagglutinating portion of Clostridium difficile toxin A has been synthesized and used to produce antisera in rabbits. Antipeptide antibody inhibited toxin A-mediated hemagglutination and neutralized cytotoxic activity. Immunoblot analysis with the antipeptide antibody revealed cross-reactivity with native toxin, a recombinant protein containing the toxin A repeats, and a glucan-binding protein from Streptococcus mutans whose primary structure has repeating amino acid motifs similar to those of the synthetic peptide. A polyclonal antibody against the glucan-binding protein, which cross-reacted with purified toxin A, also inhibited toxin A-mediated hemagglutination and neutralized cytotoxic activity. We recently identified toxin A and the glucan-binding protein as members of a novel family of clostridial and streptococcal binding proteins based on conserved repeating amino acid motifs at the C-terminal region of the molecules. This study provides immunological and functional evidence of the predicted relationship between toxin A and the glucan-binding protein and further implicates the repeating subunits as ligand-binding domains in this family of proteins.
已合成艰难梭菌毒素A血凝部分的一段含10个氨基酸的重复序列，并用于在兔体内产生抗血清。抗肽抗体抑制了毒素A介导的血凝反应并中和了细胞毒性活性。用抗肽抗体进行的免疫印迹分析显示，其与天然毒素、一种含有毒素A重复序列的重组蛋白以及变形链球菌的一种葡聚糖结合蛋白发生交叉反应，该葡聚糖结合蛋白的一级结构具有与合成肽相似的重复氨基酸基序。一种针对该葡聚糖结合蛋白的多克隆抗体，其与纯化的毒素A发生交叉反应，也抑制了毒素A介导的血凝反应并中和了细胞毒性活性。基于分子C末端区域保守的重复氨基酸基序，我们最近将毒素A和葡聚糖结合蛋白鉴定为梭菌和链球菌结合蛋白新家族的成员。本研究提供了毒素A与葡聚糖结合蛋白之间预测关系的免疫学和功能证据，并进一步表明重复亚基是该蛋白家族中的配体结合结构域。
