CERELA   05438
CENTRO DE REFERENCIA PARA LACTOBACILOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Lactocin Lac705 stimulates the activity of toxin ReIE in Lactobacillus curvatus CRL 705
Autor/es:
CECILIA ARISTIMUÑO FICOSECO; LUCRECIA TERÁN; CECILIA RODRÍGUEZ; GRACIELA VIGNOLO; RAÚL RAYA
Lugar:
Egmond aan Zee, The Netherlands
Reunión:
Simposio; 11th International Symposium on Lactic Acid Bacteria; 2014
Institución organizadora:
Royal Netherlands Society for Microbiology (KNVM) and the Federation of European Microbiological Societies(FEMS)
Resumen:
Type II toxin-antitoxin (TA) modules consist of a pair of genes that encodes two components: a stable toxin and a labile antitoxin. The toxin is co-expressed and neutralized with their cognate antitoxin from a TA operon in normally growing cells. Under stress conditions, the antitoxin is readily degraded allowing the toxin to exert their toxic effect causing the cell death. Plasmid pRC18 (18,6 kb) of Lactobacillus curvatus CRL 705 encodes a type II TA system and also the two-component bacteriocin lactocin Lac705. The TA module is a single operon that includes a 92-amino-acids antitoxin and a 118-amino-acids toxin that belong, respectively, to the superfamilies PhdYeFM and RelE. In this work, we describe that sub-inhibitory concentrations of lactocin Lac705 increases the toxic effect of RelE toxin in lactocin Lac705-sensitive cells. Strains AR3 and Sac7, two Lac705-/s mutants derived from strain CRL705, showed different sensitivity to the action of lactocin Lac705, being Sac7 four-times more sensitive than AR3. The difference between both cells is that strain Sac7 still has the plasmid pRC18 while strain AR3 is a plasmid-cured derivative. It was observed that sensitivity to Lac705 increased in AR3 cells transformed with plasmid pRA1ta, a plasmid which contains the pRC18-TA functions, showing that the TA module of pRC18 is responsible for the greater sensitivity of Sac7 to Lac705. Similar results were observed when other bacteriocins and antibiotics that target the cell membrane and cell wall functions, which suggest that the toxic function of the toxin RelE could be induced by stress factors whose mechanism of action is associated to the cell envelope.