BACTERIOPHAGE-TUC2009 AND THEIR USE FOR SITE-SPECIFIC PLASMID INTEGRATION IN THE CHROMOSOME OF TUC2009-RESISTANT LACTOCOCCUS-LACTIS-MG1363

The DNA sequence of the int-attP region of the small-isometric-headed lactococcal bacteriophage Tuc2009 is presented. In this region, an ope n reading frame, int, which potentially encodes a protein of 374 amino acids, representing the Tuc2009 integrase, was identified. The nucleo tide sequence of the bacteriophage attachment site, attP, and the sequ ences of attB, attL, and attR in the lysogenic host Lactococcus lactis subsp. cremoris UC509 were determined. A sequence almost identical to the UC509 attB sequence was found to be present in the plasmid-free T uc2009-resistant L. lactis subsp. cremoris MG1363. This site could be used for the site-specific integration of a plasmid carrying the Tuc20 09 int-attP region in the chromosome of MG1363, thereby demonstrating that the application of chromosomal insertion vectors based on bacteri ophage integration functions is not limited to the prophage-cured orig inal host strain of the phage.