title: The H35A mutated alpha-toxin interferes with cytotoxicity of staphylococcal alpha-toxin.
abstract: Staphylococcal alpha-toxin is an important virulence factor for Staphylococcus aureus to cause severe infections. In this study, we explored whether the toxoid of alpha-toxin may be utilized to block the toxicity of wild-type alpha-toxin. We created a series of H35A mutated alpha-toxin expression strains and revealed that the H35A mutation eliminates the activity of alpha-toxin using a human lung epithelial cell line (A549). More importantly, we found that either the pretreatment or simultaneous treatment of the epithelial cells with alpha-toxin-H35A completely disrupted the cytotoxicity of alpha-toxin. Specifically, we demonstrated that alpha-toxin-H35A can effectively interfere with the pore formation and the internalization of alpha-toxin using cytotoxicity and immunofluorescence assays. In addition, we found that the removal of either the 30-amino-acid (aa) or 99-aa C-terminal region of alpha-toxin-H35A reactivated its cytotoxicity, indicating that interactions between the alanine residue at position 35 and these C-terminal regions may be associated with interrupting the toxic activity of alpha-toxin-H35A. Taken together, these results suggest that the alpha-toxin-H35A protein may be developed as a potential alternative therapeutic agent for treating early stages of S. aureus infections.
authors.affiliation: Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, St Paul, MN 55108, USA. jixxx002@umn.edu
authors.forename: Xudong
authors.initials: X
authors.lastname: Liang
authors.forename: Meiying
authors.initials: M
authors.lastname: Yan
authors.forename: Yinduo
authors.initials: Y
authors.lastname: Ji
mesh_terms: D002460:Cell Line; D005455:Fluorescent Antibody Technique; D006801:Humans; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D052899:Pore Forming Cytotoxic Proteins / Q000235:genetics* / Q000378:metabolism; D013203:Staphylococcal Infections / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D013211:Staphylococcus aureus / Q000235:genetics / Q000472:pathogenicity*; D037521:Virulence Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D052899:Pore Forming Cytotoxic Proteins; D037521:Virulence Factors