Functional Dissection of the Clostridium botulinum Type B Hemagglutinin Complex: Identification of the Carbohydrate and E-Cadherin Binding Sites
Functional Dissection of the Clostridium botulinum Type B Hemagglutinin Complex: Identification of the Carbohydrate and E-Cadherin Binding Sites
复制标题
B 型肉毒梭菌血凝素复合物的功能剖析：碳水化合物和 E-钙粘蛋白结合位点的鉴定
作者：
Yo Sugawara;Masahiro Yutani;S. Amatsu;T. Matsumura;Y. Fujinaga
肉毒杆菌神经毒素 (BoNT) 抑制运动神经末梢神经递质的释放，导致肉毒杆菌中毒，这种情况通常是由于摄入毒素或产毒素细菌引起的。 BoNT 总是通过与无毒蛋白质、无毒非血凝素 (NTNH) 结合而产生大的蛋白质复合物，并且一些毒素复合物除了 NTNH 之外还含有另一种无毒蛋白质血凝素 (HA)。已知这些辅助蛋白会显着增加毒素的口服毒性。 NTNH 对消化道的恶劣条件具有保护作用，而 HA 被认为通过肠道结合和破坏上皮屏障来促进肠道吸收毒素。 HA 的两种特定活性，即碳水化合物和 E-钙粘蛋白结合，似乎参与了这些过程；然而，这些活动在肉毒杆菌中毒发病机制中的确切作用仍不清楚。该毒素通常分为七种血清型，指定为 A 至 G。在这项研究中，我们鉴定了 B 血清型 HA 中对碳水化合物和 E-钙粘蛋白结合至关重要的氨基酸残基。我们构建了这两种活性均存在缺陷的突变体，并使用体外肠细胞培养模型检查了这些活性的关系。我们的结果表明碳水化合物和 E-钙粘蛋白的结合活性在功能和结构上是独立的。碳水化合物结合通过增强细胞表面结合来增强上皮屏障破坏活性，而 E-钙粘蛋白结合对于屏障破坏至关重要。
Botulinum neurotoxin (BoNT) inhibits neurotransmitter release in motor nerve endings, causing botulism, a condition often resulting from ingestion of the toxin or toxin-producing bacteria. BoNTs are always produced as large protein complexes by associating with a non-toxic protein, non-toxic non-hemagglutinin (NTNH), and some toxin complexes contain another non-toxic protein, hemagglutinin (HA), in addition to NTNH. These accessory proteins are known to increase the oral toxicity of the toxin dramatically. NTNH has a protective role against the harsh conditions in the digestive tract, while HA is considered to facilitate intestinal absorption of the toxin by intestinal binding and disruption of the epithelial barrier. Two specific activities of HA, carbohydrate and E-cadherin binding, appear to be involved in these processes; however, the exact roles of these activities in the pathogenesis of botulism remain unclear. The toxin is conventionally divided into seven serotypes, designated A through G. In this study, we identified the amino acid residues critical for carbohydrate and E-cadherin binding in serotype B HA. We constructed mutants defective in each of these two activities and examined the relationship of these activities using an in vitro intestinal cell culture model. Our results show that the carbohydrate and E-cadherin binding activities are functionally and structurally independent. Carbohydrate binding potentiates the epithelial barrier-disrupting activity by enhancing cell surface binding, while E-cadherin binding is essential for the barrier disruption.
影响因子：
5.7
作者：
Harrison, Oliver J.;Jin, Xiangshu;Hong, Soonjin;Bahna, Fabiana;Ahlsen, Goran;Brasch, Julia;Wu, Yinghao;Vendome, Jeremie;Felsovalyi, Klara;Hampton, Cheri M.;Troyanovsky, Regina B.;Ben-Shau, Avinoam;Frank, Joachim;Troyanovsky, Sergey M.;Shapiro, Lawrence;Honig, Barry
通讯作者：
Honig, Barry