CONICET | Buscador de Institutos y Recursos Humanos

.O {color:black; font-size:149%;} a:link {color:#8DC765 !important;} a:active {color:#FEB80A !important;} a:visited {color:#AA8A14 !important;}    Plasmid-borne toxin-antitoxin (TA) system is composed of a stable toxin protein and an unstable antitoxin component and helps in plasmid maintenance by killing of plasmid-free segregants. The lactic acid bacterium Lactobacillus curvatus CRL 705 harbors plasmid pRC18, which is associated with the production of lactocin Lac705, a two-component bacteriocin. Although several plasmidcuring protocols have been applied to strain CRL705, no pRC18-cured derivative has been yet isolated; in some lactocin Lac705-negative mutants, plasmid pRC18 seems to undergo structural rearrangements and be in low copy-number (i.e., strain Sac7).In this study, we 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 (orf4) and a 118-amino-acids toxin (orf3); these proteins belong, respectively, to the superfamilies PhdYeFM and COG3041. Plasmid maintenance functions of the putative TA locus on pRC18 may explain the remarkable stability of this plasmid.

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