Alternative interactions between the Tn7 transposase and the Tn7 target DNA binding protein regulate target immunity and transposition

AUTOR(ES)

Skelding, Zachary

FONTE

Oxford University Press

RESUMO

The Tn7 transposon avoids inserting into a target DNA that contains a pre-existing copy of Tn7. This phenomenon, known as ‘target immunity’, is established when TnsB, a Tn7 transposase subunit, binds to Tn7 sequences in the target DNA and mediates displacement of TnsC, a critical transposase activator, from the DNA. Paradoxically, TnsB–TnsC interactions are also required to promote transposon insertion. We have probed Tn7 target immunity by isolating TnsB mutants that mediate more frequent insertions into a potentially immune target DNA because they fail to provoke dissociation of TnsC from the DNA. We show that a single region of TnsB mediates the TnsB–TnsC interaction that underlies both target immunity and transposition, but that TnsA, the other transposase subunit, channels the TnsB–TnsC interaction toward transposition.

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