Recent Papers

ABSTRACT

A 3372 bp insertion sequence ISPpu12 has been identified on the archetypal toluene-xylene TOL catabolic plasmid pWW0 from Pseudomonas putida mt-2. The IS element is located on the plasmid between coordinates 84397-87768 in a region which also contains the termini and transposase genes of the catabolic transposons Tn4651 and Tn4653. ISPpu12 has terminal inverted repeats of 24 bp with three mismatches and contains four open reading frames, a tnpA homologue and three lspA, orf1, and orf2 of unknown function. By ligation of a Km^r cassette into the intergenic region between orf1 and orf2, and insertion into a suicide vector, the modified ISPpu12-Km has been shown to transpose at high frequency, often in multiple copies, into the chromosome of a P. putida recipient. Inactivation of lspA, orf1 and orf2 by insertion of a 7 bp deletion into the 5' region of each gene had no major effect upon transposition but similar mutation of tnpA completely eliminated transposition. Analysis of the literature and of strains of the chlorobenzoate-degrading Pseudomonas B13 suggests that the promiscuity of this element has played an important role in the history of plasmid pWW0. Database comparisons and the accompanying paper (Weightman et al., 2002) suggest that ISPpu12 is a transposable element also found in other bacteria.