Nucleotide sequence and analysis of pRC12 and pRC18, two theta-replicating plasmids harbored by Lactobacillus curvatus CRL 705

TERÁN, LUCRECIA C.; CUOZZO, SERGIO A.; ARISTIMUÑO FICOSECO, MARÍA C.; FADDA, SILVINA; CHAILLOU, STÉPHANE; CHAMPOMIER-VERGÈS, MARIE-CHRISTINE; ZAGOREC, MONIQUE; HÉBERT, ELVIRA M.; RAYA, RAÚL R.

PLOS ONE

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2020 vol. 15

1932-6203

Thenucleotide sequences of pRC18 and pRC12, two plasmids harbored by thebacteriocin-producing strain Lactobacilluscurvatus CRL 705, were determined and analyzed. Both plasmids belong to thetheta-type replicating group. pRC12 is a pUCL287-like plasmid that consists in repA and repB genes for replication while pRC18 replicates using RepB, a 168amino acid replication protein, which has not been previously reported. pRC18 alsoharbors a pUCL287-like RepA gene, but is disrupted by a 11 Kb DNA fragment, whereRepB, several transposases/IS elements, and the lactocin Lac705 operon arelocated. These plasmids were found to be of low copy number by quantitativereal time PCR. A comparative analysis between pRC12 and pRC18 showed, a regionwith identities higher than 83%, which includes RepA, a toxin-antitoxin systemType II and a tyrosine integrase. The replicator region of pRC18 was cloned andthe recombinant plasmid, named p3B1 (CmR), was used to define the hostrange of RepB. Chloramphenicol-resistant recombinants were recovered from Lactobacillus plantarum CRL 691, Lactobacillus sakei 23K and Lactobacillus curvatus CRL 1890, a curedderivative of strain CRL 705, but not from Lactococcuslactis NZ9000. The segregational stability test showed that after 100generations, at 30ºC, >47% of recombinant clones of the mentioned strainslost p3B1.