IS1675, a novel lactococcal insertion element, forms a transposon-like structure including the lacticin 481 lantibiotic operon

Two copies of IS1675, a novel lactococcal insertion element from the IS4 fa mily, are present on a 70-kb plasmid, where they frame the lantibiotic lact icin 481 operon, The whole structure could be a composite transposon design ated Tn5721. This study shows that the lacticin 481 operon does not include any regulatory gene and provides a new example of a transposon-associated bacteriocin determinant. We identified five other IS1675 copies not associa ted with the lacticin 481 operon, The conservation of IS1675 flanking seque nces suggested a 24-bp target site.