Characterization of the integrase gene and attachment site for the Myxococcus xanthus bacteriophage Mx9.

Bacteriophage Mx9 is a temperate phage that infects Myxococcus xanthus. It lysogenizes the bacteria by integrating into the bacterial chromosome by site-specific recombination at one of two sites, attB1 or attB2. Integration at attB1 results in deletion of DNA between the two attB sites. The attB2 site lies within the 5' region of the M. xanthus tRNA(Gly) gene. Mx9 integration requires a single protein, Int. Analysis of integration revealed that the phage attachment site (attP) is contained in the int gene and that upon integration, the 3' end of the int gene is altered. Plasmids containing fusions of the pilA or mgl promoter to lacZ integrated at either Mx9 attB site have higher levels of transcription than the same fusions integrated at the Mx8 attB site.