关键词： CRISPR screen Clostridium sordellii Paeniclostridium sordellii TcsL bacterial toxin large clostridial toxin semaphorin semaphorin 6,Clostridium difficile

Mesh ： A549 Cells Animals Bacterial Proteins Bacterial Toxins / metabolism Binding Sites CRISPR-Cas Systems Cell Line, Tumor Clostridium sordellii / genetics metabolism Clustered Regularly Interspaced Short Palindromic Repeats Endothelial Cells / metabolism Female Gene Knockout Techniques HeLa Cells Humans Lung Neoplasms Male Mice Protein Binding Semaphorins / genetics isolation & purification metabolism Virulence Factors / metabolism

来  源：   DOI：10.1016/j.chom.2020.03.007   PDF(Sci-hub)   PDF(Pubmed)

Abstract：
The exotoxin TcsL is a major virulence factor in Paeniclostridium (Clostridium) sordellii and responsible for the high lethality rate associated with P. sordellii infection. Here, we present a genome-wide CRISPR-Cas9-mediated screen using a human lung carcinoma cell line and identify semaphorin (SEMA) 6A and 6B as receptors for TcsL. Disrupting SEMA6A/6B expression in several distinct human cell lines and primary human endothelial cells results in reduced TcsL sensitivity, while SEMA6A/6B over-expression increases their sensitivity. TcsL recognizes the extracellular domain (ECD) of SEMA6A/6B via a region homologous to the receptor-binding site in Clostridioides difficile toxin B (TcdB), which binds the human receptor Frizzled. Exchanging the receptor-binding interfaces between TcsL and TcdB switches their receptor-binding specificity. Finally, administration of SEMA6A-ECD proteins protects human cells from TcsL toxicity and reduces TcsL-induced damage to lung tissues and the lethality rate in mice. These findings establish SEMA6A and 6B as pathophysiologically relevant receptors for TcsL.
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