Department of Life Sciences, University of Bath, Claverton Down, Bath BA2 7AY, UK.
Protein Sciences Department, Ipsen Bioinnovation Limited, 102 Park Drive, Milton Park, Abingdon OX14 4RY, UK.
Int J Mol Sci. 2023 Aug 12;24(16):12721. doi: 10.3390/ijms241612721.
neurotoxins (BoNTs) are the most potent toxins known, causing the deadly disease botulism. They function through Zn-dependent endopeptidase cleavage of SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins, preventing vesicular fusion and subsequent neurotransmitter release from motor neurons. Several serotypes of BoNTs produced by (BoNT/A-/G and/X) have been well-characterised over the years. However, a BoNT-like gene (homologue of BoNT) was recently identified in the non-clostridial species, which is the leading cause of hospital-acquired multi-drug resistant infections. Here, we report the crystal structure of the catalytic domain of a BoNT homologue from (LC/En) at 2.0 Å resolution. Detailed structural analysis in comparison with the full-length BoNT/En AlphaFold2-predicted structure, LC/A (from BoNT/A), and LC/F (from BoNT/F) revealed putative subsites and exosites (including loops 1-5) involved in recognition of LC/En substrates. LC/En also appears to possess a conserved autoproteolytic cleavage site whose function is yet to be established.
神经毒素（BoNTs）是已知最有效的毒素，可导致致命疾病肉毒中毒。它们通过 Zn 依赖性内切酶切割 SNARE（可溶性 N-乙基马来酰亚胺敏感因子附着蛋白受体）蛋白起作用，从而阻止囊泡融合和随后的运动神经元中神经递质的释放。多年来，已经对多种由（BoNT/A-/G 和/X）产生的 BoNT 血清型进行了很好的描述。然而，最近在非梭菌属物种中发现了一种类似于 BoNT 的基因（BoNT 同源物），这是医院获得性多药耐药感染的主要原因。在这里，我们报告了来自（LC/En）的 BoNT 同源物催化结构域的晶体结构，分辨率为 2.0 Å。与全长 BoNT/En AlphaFold2 预测结构、LC/A（来自 BoNT/A）和 LC/F（来自 BoNT/F）的详细结构分析表明，可能存在参与 LC/En 底物识别的亚位点和外位点（包括环 1-5）。LC/En 似乎还具有保守的自蛋白水解切割位点，其功能尚未确定。
