DEFECTIVE SITE-SPECIFIC INTEGRATION ELEMENTS ARE PRESENT IN THE GENOME OF VIRULENT BACTERIOPHAGE LL-H OF LACTOBACILLUS-DELBRUECKII

The phage attachment site, attP, and the integrase-encoding gene, int, are sufficient to promote site-specific integration of the temperate phage mv4 genome into the chromosome of the Lactobacillus delbrueckii host (L. Dupont, B. Boizet-Bonhoure, M. Coddeville, F. Auvray, and P. Ritzenthaler, J. Bacteriol. 177:586-595, 1995), The mv4 genome region containing these elements was compared at the nucleotide and amino aci d levels with that of the closely related virulent phage LL-H. Complex DNA rearrangements were identified; a truncated integrase gene and tw o sites homologous to the mv4 attP site were detected in the genome of the virulent phage LL-H. These observations suggest that the two phag es derive from a common temperate ancestor.