The integration machinery of ZAM, a retroelement from Drosophila melanogaster, acts as a sequence-specific endonuclease

Retroviruses and retrotransposons insert into the host genome with no obvio us sequence specificity. We examined the target sites of the retroelement Z AM by sequencing each host-ZAM junction in the genome of Drosophila melanog aster. Our overall data provide compelling evidence that ZAM integration ma chinery recognizes and leads to ZAM insertion into the sequence 5'-GCGCGCg- 3'. This unique property of ZAM will facilitate the development of new tool s to study the integration process of retroelements.