SITE-SPECIFIC INTEGRATION OF THE HAEMOPHILUS-INFLUENZAE BACTERIOPHAGEHP1 - IDENTIFICATION OF THE POINTS OF RECOMBINATIONAL STRAND EXCHANGEAND THE LIMITS OF THE HOST ATTACHMENT SITE

Isotopic transfer experiments and boundary replacement studies were us ed to define the size and cleavage points of the Haemophilus influenza e attB site for phage HP1 integration. The points of strand cleavage a nd transfer were separated by 5' extensions with a spacing or overlap region most probably 7 residues long. The complete HP1 attB site is in cluded within an 18-base pair (bp) sequence surrounding the cleavage s ites. The sequence of HP1 attB is remarkably symmetric. Two 8-bp inver ted repeats surround the central residue of the 7-bp overlap sequence; this central residue is the second residue of the anticodon sequence of the H. influenzae tRNA(leu)(UUR) gene which contains attB, and this symmetric segment encodes the anticodon stem and loop.