SEQUENCE-ANALYSIS AND COMPARISON OF INT-GENE AND XIS-GENE FROM STAPHYLOCOCCAL BACTERIOPHAGE-L54A AND PHI-11

The DNA fragment encoding the integrase and excisionase genes involved in site-specific recombination of staphylococcal bacteriophage φ11 was cloned and sequenced. The int and xis genes and the recombination site, attP, were higly clustered in a 1.7-kilobase DNA fragment with the gene order attP-int-xis. The int and xis genes were transcribed divergently, with the int gene transcribed toward the attp site and the xis gene transcribed away from the attP site. The deduced Int is a basic protein of 348 residues with an estimated molecular weight of 41, 357. In contrast, the deduced Xis is an acidic protein containing 66 amino acids with an estimated molecular weight of 7,621. The site-specific recombination system of φ11 was compared with that of a closely related bacteriophage, L54a.