A composite transposon, Tn4731, associated with IS630 has been shown to transpose preferentially to 5'-TA-3' sequences that are located at two sites in a rho-dependent transcription terminator in plasmid ColE1 in Escherichia coli (T. Tenzen, S. Matsutani, and E. Ohtsubo, J. Bacteriol. 172:3830-3836, 1990). Here we demonstrated that Tn4731 preferentially transposes to TA sequences at four sites ...