Effects of deletions in transposon Tn7 on its frequency of transposition

Deletions in transposon Tn7 either abolished transposition or reduced transposition frequency. Except for a deletion in the right-hand terminus, these deletions could be complemented in trans. A 2.1-kilobase fragment of Tn7 encodes a diffusible gene product which stimulates transposition above the wild-type frequency. No cointegrate formation was detected.