Differential Roles of the Two-Component Peptides of Lactocin 705 in Antimicrobial Activity

Abstract

Lactobacillus casei CRL705 produces a class IIb bacteriocin, lactocin 705, which relies on the complementary action of two components, Lac705alpha and Lac705beta. These peptides exert a bactericidal effect on the indicator strain Lactobacillus plantarum CRL691, with an optimal Lac705alpha/Lac705beta 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 Lac705beta peptide alone. Furthermore, Lac705beta increased the inhibitory action of a diluted supernatant of L. casei CRL705, while Lac705alpha protected CRL691 cells from inhibition. Both peptides were required to dissipate the proton motive force (Deltapsi and DeltapH) of CRL691 cells. These data suggested that of the two components of lactocin 705, the Lac705alpha peptide is responsible for receptor recognition, and the Lac705beta peptide is the active component on the cell membrane of CRL691 cells.

Lactobacillus plantarum Bacteriophage LP65: a New Member of the SPO1-Like Genus of the Family Myoviridae

“…2D and E). They resembled the structures observed in L. plantarum exposed to bacteriocins, suggestive of a cellular stress reaction to phage infection (13). Alternatively, the physical penetration of the phage DNA itself might also cause the convolution of the membranes.…”

Molecular View by Fourier Transform Infrared Spectroscopy of the Relationship between Lactocin 705 and Membranes: Speculations on Antimicrobial Mechanism

“…Lactocin 705 exerted an inhibitory effect on the indicator strain Lactobacillus plantarum CRL691 with an optimal Lac705␣/Lac705␤ peptide ratio of 1 to 4. Neither Lac705␣ nor Lac705␤ displayed bacteriocin activity by itself when the growth of sensitive cells was monitored (18). Both peptides were required to dissipate the proton motive force of energized cells of Lactobacillus plantarum CRL691 (15).…”

“…Many bacteriocins appear to elicit their lethal effects by permeabilizing the cell membrane of target organisms, in certain cases by targeting intermediates of cell wall biosynthesis (10,44) or possibly proteins of the sugar phosphotransferase systems (24,39). The meat isolate Lactobacillus curvatus CRL705 (formerly identified as Lactobacillus casei CRL705) produces lactocin 705, a small antimicrobial substance that belongs to the class IIb bacteriocins, whose activities depend upon the complementation of two peptides, termed Lac705␣ (GMSGYIQGIPDFLKGYLHGISAANKHK KGRLGY; pI ϭ 9.87) and Lac705␤ (GFWGGLGYIAGRVG AAYGHAQASANNHHSPING; pI ϭ 8.61) (17,18). Lactocin 705 exerted an inhibitory effect on the indicator strain Lactobacillus plantarum CRL691 with an optimal Lac705␣/Lac705␤ peptide ratio of 1 to 4.…”

Bacteriocin (Mutacin) Production by Streptococcus mutans Genome Sequence Reference Strain UA159: Elucidation of the Antimicrobial Repertoire by Genetic Dissection

“…The bacteriocins produced by the oral bacterium Streptococcus mutans are termed mutacins and are divided into two groups: (i) the lanthionine-containing (lantibiotic) mutacins (6,11,16,19,20) and (ii) the unmodified mutacins (2,21). While most bacteriocin activities characterized to date consist of a single active polypeptide, several two-component lantibiotic and nonlantibiotic bacteriocins have also been described, and these are dependent upon the collaborative activity of two polypeptides to exert their full antimicrobial activity (7,9,14,15,17,23). Although in most cases both peptides act synergistically to effect target cell death, exceptions have been noted.…”