title: Repair of a Bacterial Small β-Barrel Toxin Pore Depends on Channel Width.
abstract: Membrane repair emerges as an innate defense protecting target cells against bacterial pore-forming toxins. Here, we report the first paradigm of Ca2+-dependent repair following attack by a small β-pore-forming toxin, namely, plasmid-encoded phobalysin ofPhotobacterium damselaesubsp.damselaeIn striking contrast,Vibrio choleraecytolysin, the closest ortholog of phobalysin, subverted repair. Mutational analysis uncovered a role of channel width in toxicity and repair. Thus, the replacement of serine at phobalysin´s presumed channel narrow point with the bulkier tryptophan, the corresponding residue inVibrio choleraecytolysin (W318), modulated Ca2+influx, lysosomal exocytosis, and membrane repair. And yet, replacing tryptophan (W318) with serine inVibrio choleraecytolysin enhanced toxicity. The data reveal divergent strategies evolved by two related small β-pore-forming toxins to manipulate target cells: phobalysin leads to fulminant perturbation of ion concentrations, closely followed by Ca2+influx-dependent membrane repair. In contrast,V. choleraecytolysin causes insidious perturbations and escapes control by the cellular wounded membrane repair-like response.IMPORTANCEPrevious studies demonstrated that large transmembrane pores, such as those formed by perforin or bacterial toxins of the cholesterol-dependent cytolysin family, trigger rapid, Ca2+influx-dependent repair mechanisms. In contrast, recovery from attack by the small β-pore-formingStaphylococcus aureusalpha-toxin or aerolysin is slow in comparison and does not depend on extracellular Ca2+To further elucidate the scope of Ca2+influx-dependent repair and understand its limitations, we compared the cellular responses to phobalysin andV. choleraecytolysin, two related small β-pore-forming toxins which create membrane pores of slightly different sizes. The data indicate that the channel width of a small β-pore-forming toxin is a critical determinant of both primary toxicity and susceptibility to Ca2+-dependent repair.
authors.affiliation: Institute of Medical Microbiology and Hygiene, University Medical Center, Johannes Gutenberg University, Mainz, Germany.
authors.forename: Gisela
authors.initials: G
authors.lastname: von Hoven
authors.affiliation: Institute of Medical Microbiology and Hygiene, University Medical Center, Johannes Gutenberg University, Mainz, Germany.
authors.forename: Amable J
authors.initials: AJ
authors.lastname: Rivas
authors.affiliation: Institute of Medical Microbiology and Hygiene, University Medical Center, Johannes Gutenberg University, Mainz, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Neukirch
authors.affiliation: Institute of Medical Microbiology and Hygiene, University Medical Center, Johannes Gutenberg University, Mainz, Germany.
authors.forename: Martina
authors.initials: M
authors.lastname: Meyenburg
authors.affiliation: Institute of Medical Microbiology and Hygiene, University Medical Center, Johannes Gutenberg University, Mainz, Germany.
authors.forename: Qianqian
authors.initials: Q
authors.lastname: Qin
authors.affiliation: Max Planck Institute for Polymer Research, Mainz, Germany.
authors.forename: Sapun
authors.initials: S
authors.lastname: Parekh
authors.affiliation: Institute of Molecular Biophysics, Faculty of Biology, Johannes Gutenberg University Mainz, Mainz, Germany nhellmann@uni-mainz.de husmann@uni-mainz.de.
authors.forename: Nadja
authors.initials: N
authors.lastname: Hellmann
authors.affiliation: Institute of Medical Microbiology and Hygiene, University Medical Center, Johannes Gutenberg University, Mainz, Germany nhellmann@uni-mainz.de husmann@uni-mainz.de.
authors.forename: Matthias
authors.initials: M
authors.lastname: Husmann
mesh_terms: D001427:Bacterial Toxins / Q000737:chemistry* / Q000378:metabolism; D002118:Calcium; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D058608:Nanopores; D054353:Perforin / Q000378:metabolism*; D014734:Vibrio cholerae / Q000737:chemistry
chemical_list: D001427:Bacterial Toxins; D054353:Perforin; D002118:Calcium