CERELA   05438
CENTRO DE REFERENCIA PARA LACTOBACILOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
The toxin-antitoxin system of plasmid prc18 increases the sensitivity of the Lactobacillus curvatus strain sac7 to lactocin705
Autor/es:
ARISTIMUÑO FICOSECO MARÍA; BLECKWEDEL, JULIANA; VIGNOLO, GRACIELA; RAYA, RAÚL
Lugar:
San Miguel de Tucuman
Reunión:
Simposio; IV International Symposium on Lactic Acid Bacteria: Food, Health and Applications; 2013
Institución organizadora:
CERELA-CONICET
Resumen:
Type II toxin‐antitoxin (TA) modules consist of a pair of genes that encode two components: a stable toxin and a labile antitoxin. The toxin is co‐expressed and neutralized with their cognate antitoxin from a TA (toxin‐antitoxin) 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. The lactic acid bacterium Lactobacillus curvatus CRL 705 harbors plasmid pRC18, which is associated with the production of Lactocin Lac705, a two‐component bacteriocin. Recent sequencing studies describe the presence of a putative TA module (partitioning locus) on plasmid pRC18, which is organized in a single operon that produces a 92‐amino‐acids antitoxin (orf3) and a 118‐amino‐acids toxin (orf2); these proteins belong, respectively, to the superfamilies PhdYeFM and RelE. In this work, we describe that AR3 and Sac7 (Lac‐/ Lacs), two mutants derived from the L. curvatus strain CRL705, showed different sensitivity to the action of the bacteriocin Lactocin 705, being more sensitive the strain Sac7 than the strain AR3. The difference between both cells is that the strain Sac7 still has the plasmid pRC18 while the strain AR3 is a plasmid‐cured derivative. Although the toxin‐antitoxin system of plasmid pRC18 could not be associated with stable plasmid maintenance, as described in other systems, our data suggest the TA module of pRC18 is responsible for the greater sensitivity of Sac7 to Lac705. AR3 cells transformed with plasmid pRA1ta, a derivative of plasmid p3B1 which contains the pRC18‐TA functions, were more sensitive to Lac705 than the wild type strain AR3 and AR3 cells transformed with the empty plasmid p3B1. These results suggest that the toxic function of the toxin could be induced by stress factors like the bacteriocin Lactocina Lac705.