title: Granzyme B translocates across the lipid membrane only in the presence of lytic agents.
abstract: Granzyme B (GrB), a component of the cytotoxic cell granule secretion pathway, is designed to kill infected and transformed cells after intracellular delivery by the pore forming protein, perforin. The mechanism of the delivery remains speculative. In this study we tested the hypothesis that GrB possesses capacity to bind and disrupt lipid membranes. Here in comparison to previous studies that show GrB interacts with carbohydrate moieties, the protease does not bind membrane phospholipids nor has intrinsic membranolytic properties. To study the transmembrane movement of GrB, we developed a model membrane system consisting of a high-molecular weight GrB substrate encapsulated in unilamellar vesicles. Intra-vesicle proteolysis clearly requires concentrations of lytic agents (streptolysin O, perforin or Triton X-100) that disrupt unilamellar membranes.
authors.affiliation: Department of Biology, Biotechnical Faculty, University of Ljubljana, Vecna pot 111, 1000 Ljubljana, Slovenia.
authors.forename: Mojca Podlesnik
authors.initials: MP
authors.lastname: Besenicar
authors.forename: Sunil
authors.initials: S
authors.lastname: Metkar
authors.forename: Baikun
authors.initials: B
authors.lastname: Wang
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Froelich
authors.forename: Gregor
authors.initials: G
authors.lastname: Anderluh
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry; D053804:Granzymes / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry*; D008956:Models, Chemical; D017830:Octoxynol / Q000737:chemistry; D054353:Perforin / Q000737:chemistry; D013301:Streptolysins / Q000737:chemistry; D053835:Unilamellar Liposomes / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D008055:Lipids; D013301:Streptolysins; D053835:Unilamellar Liposomes; C025964:streptolysin O; D054353:Perforin; D017830:Octoxynol; D053804:Granzymes