Nucleotide sequences of the attachment sites of bacteriophage Mu DNA

Abstract

THE temperate bacteriophage Mu has the remarkable ability to insert its DNA in apparently random sites of the Escherichia coli chromosome (1–3). All Mu prophages have the same gene order4, and the finding that the prophage and the phage maps are identical suggests that specific sites (attachment sites) at the ends of the Mu genome are used for the integration of Mu5. Phage particles do not contain the excised, free form of the Mu DNA; instead, the Mu genome is flanked by what seems to be heterogeneous bacterial DNA6,7. The variable DNA at both ends of Mu is thought to be generated when Mu DNA is transposed to many new chromosomal sites during replication and is subsequently packaged into phage particles together with adjacent host DNA. The nucleotide sequence analysis of the ends of Mu DNA reported here substantiates this hypothesis and identifies the attachment sites of Mu. Structural features of the attachment sites are presented.