The effect of tnm mutations of Escherichia coli K12 on transposition of various movable genetic elements.

The effects of different tnm mutations on the transposition of Tn3, Tn5, Tn10, Tn601, and bacteriophage Mu were studied. Five tnm mutations were placed into three phenotypic classes. The representatives of the first class, tnm-1 and tnm-2, caused a complete block of transposition of all Tn-elements studied; the representatives of the second class, tnm-3 and tnm-4, specifically affected Tn9 transposition while the tnm-5 mutation attributed to the third class caused formation of cointegrates between the donor genome of phage lambda carrying Tn-elements Tn3 or Tn5 and the recipient genome (bacterial chromosome).