title: Mode of action of lactocin 705, a two-component bacteriocin from Lactobacillus casei CRL705.
abstract: Lactocin 705 is a bacteriocin whose activity depends on the complementary action of two peptides (705alpha and 705beta) of 33-amino-acid residues each and is produced by Lactobacillus casei CRL705. Biologically active, synthetic lactocin 705 was used to study the mode of action on sensitive cells of Lactobacillus plantarum CRL691. The addition of 90 nmol l(-1) of lactocin 705 to cells of L. plantarum dissipated both, the membrane potential (DeltaPsi) and the pH gradient (DeltapH). Energized membrane, obtained after the addition of glucose, were more susceptible to lactocin 705 action leading to the immediate release of intracellular K(+) and inorganic phosphate. When the role of various ions on sensitive cells were analyzed, only Ca(2+) ion exhibited a protective effect against lactocin 705. These data suggest that the presence of a proton motive force (PMF) promotes the interaction of the bacteriocin with the cytoplasmic membrane of energized cells, leading to pore formation which allows for the efflux of ions, thereby ensuring efficient killing of target bacteria.
authors.affiliation: Centro de Referencia para Lactobacilos (CERELA), CONICET, Chacabuco 145, 4000, Tucumán, Argentina.
authors.forename: Patricia
authors.initials: P
authors.lastname: Castellano
authors.forename: Raul
authors.initials: R
authors.lastname: Raya
authors.forename: Graciela
authors.initials: G
authors.lastname: Vignolo
mesh_terms: D001430:Bacteriocins / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D007778:Lactobacillus / Q000254:growth & development; D007780:Lacticaseibacillus casei / Q000378:metabolism*; D008564:Membrane Potentials / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D011188:Potassium / Q000378:metabolism
chemical_list: D001430:Bacteriocins; C035728:lactocin; D011188:Potassium; D002118:Calcium