A Transposable Phage Bacteriophage Mu

Lytic growth of Mu can occur either upon initial infection, if the c gene repressor is not formed, or by induction of a lysogen. In either case, replication of Mu DNA involves repeated transposition of Mu to multiple sites on the host genome. Initially, transcription of only the early genes of Mu occurs, but after gene C protein, a positive activator of late RNA synthesis, is expressed, the synthesis of the Mu head and tail proteins occurs. Eventually, expression of the lytic function occurs and mature phage particles are released. 

Because Mu integrates at a wide variety of host sites, it can be used to induce mutants at many locations. Also, Mu can be used to carry into the cell genes that have been derived from other host cells, a form of in vivo genetic engineering. In addition, modified Mu phage have been made artificially in which some of the harmful functions 

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