Transposon Tn3-mediated replicon fusion.

ABSTRACT

To investigate inter-replicon transposition of Tn3, we used the cosmid-phage lambda packaging system coupled with density gradient fractionation and isolated recombinant molecules of different sizes. Cosmids derived from ampicillin-resistance-transducing phage were classified into four groups (1) cosmid-Tn3 donor cointegrates considered as Tn3 transposition intermediates, (2) similar cointegrates carrying deletions of one copy of Tn3 and of adjacent cosmid DNA sequences, (3) cosmids carrying a single Tn3 insertion, and (4) cosmids carrying two independent Tn3 insertions. Genetic and biochemical studies indicated that cosmids isolated from ampicillin-resistance transductants were derived from the authentic cosmid-Tn3 donor cointegrate intermediates.