A novel subunit structure of Clostridium botulinum serotype D toxin complex with three extended arms
A novel subunit structure of Clostridium botulinum serotype D toxin complex with three extended arms
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DOI：
10.1074/jbc.m703446200
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发表时间：
2007-08-24
影响因子：
4.8
通讯作者：
Ohyama, Tohru
中科院分区：
文献类型：
--
作者：
Hasegawa, Kimiko;Watanabe, Toshihiro;Ohyama, Tohru
肉毒杆菌神经毒素 (BoNT) 是自然界中已知的最有效的毒素，可导致人类和动物致命的肉毒杆菌中毒。 BoNT 通过抑制胆碱能突触释放神经递质发挥作用。肉毒梭菌菌株产生大型 BoNT 毒素复合物，其中包括辅助无毒蛋白质，这些蛋白质不仅可以保护 BoNT 免受消化道恶劣环境的影响，还可以帮助 BoNT 跨肠粘膜层易位。在这项研究中，我们首次使用负染色透射电子显微镜 (TEM) 可视化一系列 D 型肉毒杆菌毒素复合物。该复合物由 150-kDa BoNT、130-kDa 无毒非血凝素 (NTNHA) 和三种血凝素 (HA) 亚组分组成：70-kDa HA-70、33-kDa HA-33 和 17-kDa HA-17。这些组件按顺序组装形成复合体。成熟的 L-TC 的新颖 TEM 图像显示出带有“三臂”的椭圆形结构。 “身体”部分由单个 BoNT、单个 NTNHA 和三个 HA-70 分子组成。臂部分由 HA-33 和 HA-17 分子的复合物组成。我们确定了由两个 HA-33 加一个 HA-17 形成的复合物的 X 射线晶体结构。根据 TEM 图像和生化结果，我们提出了一种新型的肉毒杆菌毒素复合物 14 聚体亚基模型。这种独特的模型表明无毒成分如何构成 BoNT 的“输送工具”。
The botulinum neurotoxins (BoNTs) are the most potent toxins known in nature, causing the lethal disease known as botulism in humans and animals. The BoNTs act by inhibiting neurotransmitter release from cholinergic synapses. Clostridium botulinum strains produce large BoNTs toxin complexes, which include auxiliary non-toxic proteins that appear not only to protect BoNTs from the hostile environment of the digestive tract but also to assist BoNT translocation across the intestinal mucosal layer. In this study, we visualize for the first time a series of botulinum serotype D toxin complexes using negative stain transmission electron microscopy (TEM). The complexes consist of the 150-kDa BoNT, 130-kDa nontoxic non-hemagglutinin (NTNHA), and three kinds of hemagglutinin (HA) subcomponents: 70-kDa HA-70, 33-kDa HA-33, and 17-kDa HA-17. These components assemble sequentially to form the complex. A novel TEM image of the mature L-TC revealed an ellipsoidal-shaped structure with "three arms" attached. The "body" section was comprised of a single BoNT, a single NTNHA and three HA-70 molecules. The arm section consisted of a complex of HA-33 and HA-17 molecules. We determined the x-ray crystal structure of the complex formed by two HA-33 plus one HA-17. On the basis of the TEM image and biochemical results, we propose a novel 14-mer subunit model for the botulinum toxin complex. This unique model suggests how non-toxic components make up a "delivery vehicle" for BoNT.