Deletion caused by Tn3: Correlation between deletion and transposition.

Abstract

A convenient system for detection of deletion formation in the DNA containing Tn3 is described. EcoRI-D fragment containing the kil gene and the c1857 gene of AcI857S7 DNA was ligated into pYS1 (a colicin El like plasmid) containing Tn3. Bacteria harboring these plasmids were temperature sensitive due to induction of the kil gene of phage A at high temperature.Survivors from these bacteria at 42°C have plasmids that have lost the kil gene activity by deletion. In certain mutants in Tn3 which we isolated, such deletion was not detected, nor was Tn3 transposition.On the other hand, in another mutant, in which BamHI site located in tnpR gene in Tn3 was eliminated , the frequency of deletion formation was enhanced, while transposition was normal. From these results, deletion can be considered to be a partial reaction of transposition.

The transposable element Tn3 promotes general recombination at the neighboring regions.

“…Insertion of Tn3 results in a 5 by repeated sequence at the site, and leads to a mutation by disrupting the continuity of the genes or operons. In addition to their translocation from a DNA molecule to another, transposons often promote deletion of DNA segments adjacent to, or within the elements (Kleckner, 1979;Ross et al, 1979a;Sugino and Kawashima, 1983). Reversion of the mutant phenotype caused by transposon-insertion may occur if the elements are excised precisely or nearly precisely (Ross et al ,1979b;Wang et al, 1980;Miller et al, 1980).…”