CERELA   05438
CENTRO DE REFERENCIA PARA LACTOBACILOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Stability of plasmid pRC18 mediated by a toxin-antitoxinn system.
Autor/es:
ARISTIMUÑO FICOSECO MC, BLECKWEDEL J, HARO C, VIGNOLO GM, RAYA RR
Lugar:
San Miguel de Tucumán
Reunión:
Congreso; VII Congreso Argentino de Microbiología General – SAMIGE del Bicentenario 2011; 2011
Institución organizadora:
SAMIGE
Resumen:
A 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. 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 (orf4) and a 118-amino-acids toxin (orf3); these proteins belong, respectively, to the superfamilies PhdYeFM and COG3041. Plasmid curing experiments showed that plasmid pRC18 was relatively stable: only 4% of CRL705 cells were plasmid free after cell growth at 39 ̊C. In contrast, 68% of CRL1597 cells, a CRL705-derivative harboring plasmid p3.3, a plasmid similar to pRC18 but that does not has the TA system, has lost their plasmid after similar growth conditions. These results suggest that plasmid maintenance functions of the putative TA locus on pRC18 may explain the remarkable stability of this plasmid. However, the TA system of pRC18 seemed to be not functional in Escherichia coli since plasmids pBlueScript SKII+ and pJR, a pBlueScript SKII+. Derivative which contains the pRC18-TA functions cloned in its EcoRI site, showed the same stability in E. coli DH5α cells. The minimal region of the TA system involved in plasmid pRC18 stability is currently evaluated in Lactobacillus curvatus AR3, a plasmid-cured derivative of CRL705.