Lac705 stimulates the activity of toxin RelE in Lactobacillus curvatus CRL705

VIGNOLO, GRACIELA; ARISTIMUÑO, CECILIA; TERÁN, MARÍA LUCRECIA; RODRÍGUEZ, MARIA CECILIA; RAYA RAÚL

Egmond aan Zee

Simposio; 11th International Symposium on Lactic Acid Bacteria. Health, Sustainability, Diversity, and Application; 2014

FEMS

e ll tox¡n-anlitoxin (TA) modules consist of a pair of genes that encodes two components: a stable toxin and a e antitoxin. The toxin is co-expressed and neutral¡zed with iheir cognate antitoxin from a TA operon in normally üng cells. Under stress conditions, the antitoxin is readily degraded allowing the tox¡n to exerttheir toxic effecf sing the cell death. Plasmid pRC18 (18,6 kb) of Lactobacillus culvafus CRL 705 encodes a type ll TA system also the two-component bacteriocin lactocin Lac705. The TA module is a single operon that includes a 92- ]o-acids antitoxin and a 1 18-amino-ac¡ds tox¡n that belong, respectively, to the superfamilies phdyeFM and i. ln this work, we describe that sub-inhibitory concentrations of lactocin Lac705 increases the toxic effect of i toxin in lactocin Lac705-sensitive cells. Strains AR3 and Sac7, two Lac705-/s mutants derived from strain -705, showed different sens¡fivity to the action of lactocin Lac705, being SacT four{imes more sensitive than i. The difference between both cells is that stra¡n SacT still has the plasmid pRC18 while strain AR3 is a plasmidd derivative. lt was observed that sensitivity to Lac705 increased in AR3 cells transformed with plasmid pM1ta, ¡smid which contains the pRC18-TA functions, showing that the TA module of pRC18 is responsible for the Iter sensitivity of SacT to Lac705. Similar results were observed when other bacteriocins and antibiotics that et the cell membrane and cell wall funct¡ons, which suggest that the toxic function of the toxin RelE could be ced by stress factors whose mechanism of action is associated to the cell envelope.