DNA sequence of the att region of coliphage 434

Phages lambda and 434 are related phages that insert at the same site on the Escherichia coli chromosome. A 5.9-kb SalI-BamHI fragment derived from phage 434 was shown to hybridize to a 0.5-kb probe carrying attP-lambda. A 0.8-kb Bam HI-TaqI fragment subcloned into pBR327 was used for sequencing. The sequence of the 500 bp around the insertion site is given here, Comparison of the lambda and 434 sequence shows that the following regions are conserved: the coding sequence for the integrase protein (only 162 bp have been sequenced corresponding to the carboxy terminus), the 15-bp common core at the insertion site, and the three integrase-binding sites flanking the insertion site. The lambda and 434 sequences diverge radically to the left of base-197, suggesting that DNA to the left of that point plays no specific role in insertion or its regulation.