Characterization of a cryptic plasmid from Lactobacillus plantarum.

The complete nucleotide sequence of pLB4, a cryptic plasmid isolated from Lactobacillus plantarum NCDO1088 has been determined. Three open reading frames, which encode proteins of 42, 25 and 6 kDa, have been identified. In vitro transcription/translation of pLB4-derived DNA restriction fragments confirm the existence of all three polypeptides, which show homology to replication proteins and site-specific recombinases from other Gram+ plasmids. Three major regions of dyad symmetry with delta G of -28.8, -15.0 and -17.0 kcal were observed. One of these regions contains a sequence which shows perfect homology to the nick site of the Gram+ replicons, pE194, pLS1 and pADB201. In addition, a 21-bp sequence located upstream from the site-specific recombinase shows 80% homology to the recombination sites of pE194 and pT181.