title: The bacterial peptide pheromone plantaricin A permeabilizes cancerous, but not normal, rat pituitary cells and differentiates between the outer and inner membrane leaflet.
abstract: Plantaricin A (PlnA) is a 26-mer peptide pheromone with membrane-permeabilizing, strain-specific antibacterial activity, produced by Lactobacillus plantarum C11. We investigated the membrane-permeabilizing effects of PlnA on cultured cancerous and normal rat anterior pituitary cells using patch-clamp techniques and microfluorometry (fura-2). Cancerous cells displayed massive permeabilization within 5 s after exposure to 10-100 microM PlnA. The membrane depolarized to nearly 0 mV, and the membrane resistance decreased to a mere fraction of the initial value after less than 1 min. In outside-out membrane patches, 10 microM PlnA induced membrane currents reversing at 0 mV, which is compatible with an unspecific conductance increase. The D and L forms of the peptide had similar potency, indicating a nonchiral mechanism for the membrane-permeabilizing effect. Surprisingly, inside-out patches were insensitive to 1 mM PlnA. Primary cultures of normal rat anterior pituitary cells were also insensitive to the peptide. Thus, PlnA differentiates between plasma membranes and membrane leaflets. Microfluorometric recordings of [Ca(2+)](i) and cytosolic concentration of fluorochrome verified the rapid permeabilizing effect of PlnA on cancerous cells and the insensitivity of normal pituitary cells.
authors.affiliation: Department of Molecular Biosciences, University of Oslo, NO 0316, Oslo, Norway.
authors.forename: Sverre L
authors.initials: SL
authors.lastname: Sand
authors.forename: Trude M
authors.initials: TM
authors.lastname: Haug
authors.forename: Jon
authors.initials: J
authors.lastname: Nissen-Meyer
authors.forename: Olav
authors.initials: O
authors.lastname: Sand
mesh_terms: D000818:Animals; D001430:Bacteriocins / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects / Q000648:ultrastructure; D002463:Cell Membrane Permeability / Q000187:drug effects*; D003592:Cytophotometry; D016257:Fura-2; D018408:Patch-Clamp Techniques; D010902:Pituitary Gland / Q000187:drug effects*; D010911:Pituitary Neoplasms; D051381:Rats
chemical_list: D001430:Bacteriocins; C084446:plantaricin A; D016257:Fura-2