The Bacterial Peptide Pheromone Plantaricin A Permeabilizes Cancerous, but not Normal, Rat Pituitary Cells and Differentiates between the Outer and Inner Membrane Leaflet |
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Authors: | Sverre L Sand Trude M Haug Jon Nissen-Meyer Olav Sand |
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Institution: | (1) Department of Molecular Biosciences, University of Oslo, NO, 0316 Oslo, Norway |
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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 μm 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 μm 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 Ca2+]
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and cytosolic concentration of fluorochrome verified the rapid permeabilizing effect of PlnA on cancerous cells and the insensitivity
of normal pituitary cells. |
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Keywords: | Antimicrobial peptide Plantaricin A Lactobacillus plantarum Anterior pituitary cells Membrane permeabilization Patch clamp |
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