Mini-Mu: An Insertion Element Derived from Temperate Phage Mu-1

Abstract

The two ends of phage Mu-1 DNA are Hnked to host DNA both in the viral particle and during the different steps of the lytic cycle (for review on Mu, see Bukhari 1976). Integration of Mu DNA, which involves replacement of the host DNA sequences present at its ends by new host sequences, is, in fact, a transposition event. The integration reaction that occurs between the two ends of Mu DNA and an apparently random site on the target DNA requires the Mu gene-A product (O'Day et al. 1978). The transposition of Mu to a new location does not involve excision of Mu DNA from its original location (Ljungquist and Bukhari 1977), suggesting that only replicas of the Mu genome are transposed. This might explain why MuB− mutants, which are unable to replicate, transpose at a lower frequency than Mu wild type (O'Day et al. 1978). Mu provokes different kinds...