title: The perforin pore facilitates the delivery of cationic cargos.
abstract: Cytotoxic lymphocytes eliminate virally infected or neoplastic cells through the action of cytotoxic proteases (granzymes). The pore-forming protein perforin is essential for delivery of granzymes into the cytoplasm of target cells; however the mechanism of this delivery is incompletely understood. Perforin contains a membrane attack complex/perforin (MACPF) domain and oligomerizes to form an aqueous pore in the plasma membrane; therefore the simplest (and best supported) model suggests that granzymes passively diffuse through the perforin pore into the cytoplasm of the target cell. Here we demonstrate that perforin preferentially delivers cationic molecules while anionic and neutral cargoes are delivered inefficiently. Furthermore, another distantly related pore-forming MACPF protein, pleurotolysin (from the oyster mushroom), also favors the delivery of cationic molecules, and efficiently delivers human granzyme B. We propose that this facilitated diffusion is due to conserved features of oligomerized MACPF proteins, which may include an anionic lumen.
authors.affiliation: From the Department of Biochemistry and Molecular Biology.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Stewart
authors.forename: Stephanie C
authors.initials: SC
authors.lastname: Kondos
authors.forename: Antony Y
authors.initials: AY
authors.lastname: Matthews
authors.forename: Michael E
authors.initials: ME
authors.lastname: D'Angelo
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Dunstone
authors.forename: James C
authors.initials: JC
authors.lastname: Whisstock
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Trapani
authors.forename: Phillip I
authors.initials: PI
authors.lastname: Bird
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001692:Biological Transport; D002412:Cations / Q000378:metabolism; D002460:Cell Line; D004058:Diffusion; D053804:Granzymes / Q000378:metabolism; D006460:Hemolysin Proteins / Q000378:metabolism; D006493:Heparin / Q000378:metabolism; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D054353:Perforin / Q000737:chemistry* / Q000378:metabolism*; D016062:Porosity; D017434:Protein Structure, Tertiary
chemical_list: D002412:Cations; D006460:Hemolysin Proteins; D054353:Perforin; D006493:Heparin; D053804:Granzymes
keywords: Cell Death; Cell Permeabilization; Cellular Immune Response; Granzyme; MACPF; Natural Killer (NK) Cell; Perforin; Pore; Streptolysin O; T Cell Biology