NUCLEOTIDE-SEQUENCE ANALYSIS OF THE TERMINI AND CHROMOSOMAL LOCUS INVOLVED IN SITE-SPECIFIC INTEGRATION OF THE STREPTOCOCCAL CONJUGATIVE TRANSPOSON-TN5252

The 47-kb, broad-host-range, streptococcal conjugative transposon Tn52 52 is capable of site-specific integration into the pneumococcal chrom osome. We present the nucleotide sequence of the terminal regions of t he transposon and its target site in the pneumococcal genome. No inver ted repeats were found at the termini of the transposon. A 72-bp regio n of the target was present on either side following the insertion of Tn5252 and appeared to serve as a signal for its integration and excis ion. The data suggest that the left copy of the 72-bp segment was a pa rt of the conjugative element, the crossover point of integration was nonrandom within this region, and the mechanism of insertion could res emble that of the site-specific temperate phages.