Mu is a fascinating bacteriophage whose genome replicates as a DNA transposon. Mu has been extensively studied and now serves as a model system for transposable elements and viruses. Mu has also became a valuable genetic tool for many biological applications including insertion mutagenesis, gene transduction and translocation, chromosome marking and mapping, DNA cloning, DNA sequencing, and gene fusing for studies of gene expression and regulation. These genetic applications also serve as models for applications of other transposons and viruses in different biological systems. Further studies and applications of Mu and related phage are proposed, with extensions to other bacterial species. Specifically, 1) the targeting of Mu transposition will be studied with fusions of the Mu B gene to the DNA binding protein gene lacI, 2) the rfa host receptor genes for the Mu and related phage will be studied in Escherichia coli and Salmonella typhimurium to understand their surface requirements for the lipopolysaccharide receptors and 3) the knowledge of their receptor specificities will be used to extend the host range of these phage and their applications to other Enterobacteriaceae.
