Differential Roles of the Two-Component Peptides of Lactocin 705 in Antimicrobial Activity |
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Authors: | Sergio A Cuozzo Patricia Castellano Fernando JM Sesma Graciela M Vignolo Raul R Raya |
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Institution: | (1) Centro de Referencia para Lactobacilos (CERELA), CONICET, Chacabuco 145, 4000 Tucumán, Argentina, AR |
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Abstract: | Lactobacillus casei CRL705 produces a class IIb bacteriocin, lactocin 705, which relies on the complementary action of two components, Lac705α
and Lac705β. These peptides exert a bactericidal effect on the indicator strain Lactobacillus plantarum CRL691, with an optimal Lac705α/Lac705β peptide ratio of 1 to 4. Electron microscopy studies showed that treated CRL691 cells
have their cell wall severely damaged, with mesosome-like membranous formations protruding into their cytoplasm. Although
less pronounced, a similar effect was also observed with the Lac705β peptide alone. Furthermore, Lac705β increased the inhibitory
action of a diluted supernatant of L. casei CRL705, while Lac705α protected CRL691 cells from inhibition. Both peptides were required to dissipate the proton motive
force (Δψ and ΔpH) of CRL691 cells. These data suggested that of the two components of lactocin 705, the Lac705α peptide is
responsible for receptor recognition, and the Lac705β peptide is the active component on the cell membrane of CRL691 cells.
Received: 12 April 2002 / Accepted: 24 May 2002 |
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