In vivo cloning of DNA into multicopy cosmids by mini-Mu-cosduction.

A general in vivo procedure for cloning Escherichia coli genes into cosmids has been developed. The method we describe here uses a deleted Mu phage (a mini-Mu) to transpose E. coli genes into cosmids during mini-Mu replication. The resulting cosmids clones are packaged in vivo into lambda phage particles. Plasmids carrying a particular DNA sequence can be selectively recovered after infection of a new host with the in vivo constructed genomic cosmid library. This system was used successfully to clone several E. coli genes.