流行的艰难梭菌毒素 B 变体的功能分析揭示了它们在利用受体和诱导病理方面的差异。
Functional analyses of epidemic Clostridioides difficile toxin B variants reveal their divergence in utilizing receptors and inducing pathology.
机构信息
Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, China.
Center for Infectious Disease Research, Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, China.
出版信息
PLoS Pathog. 2021 Jan 28;17(1):e1009197. doi: 10.1371/journal.ppat.1009197. eCollection 2021 Jan.
Clostridioides difficile toxin B (TcdB) is a key virulence factor that causes C. difficile associated diseases (CDAD) including diarrhea and pseudomembranous colitis. TcdB can be divided into multiple subtypes/variants based on their sequence variations, of which four (TcdB1-4) are dominant types found in major epidemic isolates. Here, we find that these variants are highly diverse in their receptor preference: TcdB1 uses two known receptors CSPG4 and Frizzled (FZD) proteins, TcdB2 selectively uses CSPG4, TcdB3 prefers to use FZDs, whereas TcdB4 uses neither CSPG4 nor FZDs. By creating chimeric toxins and systematically switching residues between TcdB1 and TcdB3, we determine that regions in the N-terminal cysteine protease domain (CPD) are involved in CSPG4-recognition. We further evaluate the pathological effects induced by TcdB1-4 with a mouse intrarectal installation model. TcdB1 leads to the most severe overall symptoms, followed by TcdB2 and TcdB3. When comparing the TcdB2 and TcdB3, TcdB2 causes stronger oedema while TcdB3 induces severer inflammatory cell infiltration. These findings together demonstrate divergence in the receptor preference and further lead to colonic pathology for predominant TcdB subtypes.
艰难梭菌毒素 B(TcdB)是一种关键的毒力因子,可导致艰难梭菌相关疾病(CDAD),包括腹泻和伪膜性结肠炎。根据序列变异,TcdB 可分为多个亚型/变体,其中 4 种(TcdB1-4)是主要流行分离株中的主要类型。在这里,我们发现这些变体在受体偏好上高度多样化:TcdB1 使用两种已知的受体 CSPG4 和 Frizzled(FZD)蛋白,TcdB2 选择性地使用 CSPG4,TcdB3 更喜欢使用 FZDs,而 TcdB4 既不使用 CSPG4 也不使用 FZDs。通过创建嵌合毒素并在 TcdB1 和 TcdB3 之间系统地交换残基,我们确定 N 端半胱氨酸蛋白酶结构域(CPD)中的区域参与 CSPG4 的识别。我们进一步使用小鼠直肠内安装模型评估 TcdB1-4 引起的病理效应。TcdB1 导致最严重的总体症状,其次是 TcdB2 和 TcdB3。当比较 TcdB2 和 TcdB3 时,TcdB2 引起更强的水肿,而 TcdB3 引起更严重的炎症细胞浸润。这些发现共同表明受体偏好的差异,并进一步导致主要 TcdB 亚型的结肠病理学。