DNA binding by the Xis protein of the conjugative transposon Tn916.

We purified the Xis protein of the conjugative transposon Tn916 and showed by nuclease protection experiments that Xis bound specifically to sites close to each end of Tn916. These specific binding sites are close to, and in the same relative orientation to, binding sites for the N-terminal domain of Tn916 integrase protein. These results suggest that Xis is involved in the formation of nucleoprotein structures at the ends of Tn916 that help to correctly align the ends so that excision can occur.