Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA.
mBio. 2017 May 16;8(3):e00503-17. doi: 10.1128/mBio.00503-17.
infection (CDI) is a major cause of hospital-associated, antibiotic-induced diarrhea, which is largely mediated by the production of two large multidomain clostridial toxins, TcdA and TcdB. Both toxins coordinate the action of specific domains to bind receptors, enter cells, and deliver a catalytic fragment into the cytosol. This results in GTPase inactivation, actin disassembly, and cytotoxicity. TcdB in particular has been shown to encode a region covering amino acids 1753 to 1851 that affects epitope exposure and cytotoxicity. Surprisingly, studies here show that several peptides derived from this region, which share the consensus sequence NVFKGNTISDK, protect cells from the action of TcdB. One peptide, PepB2, forms multiple interactions with the carboxy-terminal region of TcdB, destabilizes TcdB structure, and disrupts cell binding. We further show that these effects require PepB2 to form a higher-order polymeric complex, a process that requires the central GN amino acid pair. These data suggest that TcdB interacts with repeat sequences in the proximal carboxy-terminal domain of TcdB (i.e., the CROP domain) to alter the conformation of TcdB. Furthermore, these studies provide insights into TcdB structure and functions that can be exploited to inactivate this critical virulence factor and ameliorate the course of CDI. is a leading cause of hospital-associated illness that is often associated with antibiotic treatment. To cause disease, secretes toxins, including TcdB, which is a multidomain intracellular bacterial toxin that undergoes conformational changes during cellular intoxication. This study describes the development of peptide-based inhibitors that target a region of TcdB thought to be critical for structural integrity of the toxin. The results show that peptides derived from a structurally important region of TcdB can be used to destabilize the toxin and prevent cellular intoxication. Importantly, this work provides a novel means of toxin inhibition that could in the future develop into a treatment.
艰难梭菌感染（CDI）是医院相关性、抗生素诱导性腹泻的主要原因，主要由两种大型多结构域梭状芽胞杆菌毒素 TcdA 和 TcdB 产生。这两种毒素通过特定结构域的协同作用结合受体、进入细胞并将催化片段递送至细胞质。这导致 GTP 酶失活、肌动蛋白解聚和细胞毒性。特别是 TcdB 已被证明编码一个覆盖氨基酸 1753 至 1851 的区域，该区域影响表位暴露和细胞毒性。令人惊讶的是，这里的研究表明，来自该区域的几个肽段，它们共享 NVFKGNTISDK 共识序列，可保护细胞免受 TcdB 的作用。一种肽段 PepB2 与 TcdB 的羧基末端区域形成多种相互作用，使 TcdB 结构不稳定，并破坏细胞结合。我们进一步表明，这些效应需要 PepB2 形成更高阶的聚合复合物，这一过程需要中心 GN 氨基酸对。这些数据表明 TcdB 与 TcdB 近端羧基末端结构域（即 CROP 结构域）中的重复序列相互作用，从而改变 TcdB 的构象。此外，这些研究提供了对 TcdB 结构和功能的深入了解，可用于使这种关键毒力因子失活并改善 CDI 的病程。
是一种导致医院相关性疾病的主要原因，通常与抗生素治疗有关。为了引起疾病，会分泌毒素，包括 TcdB，它是一种多结构域的胞内细菌毒素，在细胞中毒过程中经历构象变化。本研究描述了针对 TcdB 被认为对毒素结构完整性至关重要的区域的基于肽的抑制剂的开发。结果表明，源自 TcdB 结构重要区域的肽段可用于使毒素失稳并防止细胞中毒。重要的是，这项工作提供了一种新的毒素抑制方法，未来可能会开发出一种治疗方法。
