ANALYSIS OF A REGION FROM THE BACTERIOPHAGE RESISTANCE PLASMID PCI528INVOLVED IN ITS CONJUGATIVE MOBILIZATION BETWEEN LACTOCOCCUS STRAINS

A 10-kb HindIII fragment of pCI528 cloned into the nonconjugative shut tle vector pCI3340 could be transferred by conjugative mobilization fr om Lactococcus lactis subsp. lactis MG1363, whereas other HindIII frag ments of pCI528 or the vector alone were nonmobilizable. Subcloning of this 10-kb region identified a 4.4-kb BglII-EcoRI fragment which cont ained all the DNA essential for transfer. Sequence analysis of a 2-kb region within this 4.4 kb-segment revealed a region rich in inverted r epeats and two potential overlapping open reading frames, one of which demonstrated homology to mobilization proteins of two nonconjugative staphylococcal plasmids.