Site-specific Recombination in Phage Mu

Integration of bacteriophage Mu into host DNA requires the expression of a specific recombination system, at least part of which is Mu encoded (Taylor 1963). The recombination event is site-specific with respect to the utilization of attachment sites located near the ends of Mu DNA; consequently, the prophage has a nonpermuted gene order. In contrast with respect to host sequences, the recombination appears to take place at random sites (Bukhari and Zipser 1972). A second site-specific recombination system is responsible for inversion of the G DNA segment of phage Mu. The G segment consists of 3000 base pairs of DNA flanked by short inverted duplications (Hsu and Davidson 1974). Inversion of the G segment is mediated by a Mu-encoded function called Gin (Kamp et al. 1978). We have described a mutant, Mu 445-5, which is unable to invert its G segment (Chow et al. 1977). This mutant can be complemented...