Characterization of the<i>Pseudomonas putida</i>Mobile Genetic Element ISPpu<i>10</i>: an Occupant of Repetitive Extragenic Palindromic Sequences

<jats:title>ABSTRACT</jats:title><jats:p>We have characterized the<jats:italic>Pseudomonas putida</jats:italic>KT2440 insertion element ISPpu<jats:italic>10</jats:italic>. This insertion sequence encodes a transposase which exhibits homology to the transposases and specific recombinases of the Piv/Moov family, and no inverted repeats are present at the borders of its left and right ends, thus constituting a new member of the atypical IS<jats:italic>110</jats:italic>/IS<jats:italic>492</jats:italic>family. ISPpu<jats:italic>10</jats:italic>was found in at least seven identical loci in the KT2440 genome, and variants were identified having an extra insertion at distinct loci. ISPpu<jats:italic>10</jats:italic>always appeared within the core of specific repetitive extragenic palindromic (REP) sequences TCGCGGGTAAACCCG<jats:underline><jats:underline>CT</jats:underline></jats:underline>CCTAC, exhibiting high target stringency. One intragenic target was found associated with the truncation of a GGDEF/EAL domain protein. After active in vitro transposition to a plasmid-borne target, a duplication of the CT (underlined above) at the junction as a consequence of the ISPpu<jats:italic>10</jats:italic>insertion was experimentally demonstrated for the first time in the IS<jats:italic>110</jats:italic>/IS<jats:italic>492</jats:italic>family. The same duplication was observed after transposition of ISPpu<jats:italic>10</jats:italic>from a plasmid to the chromosome of<jats:italic>P. putida</jats:italic>DOT-T1E, an ISPpu<jats:italic>10</jats:italic>-free strain with REPs similar to those of strain KT2440. Plasmid ISPpu<jats:italic>10</jats:italic>-mediated rearrangements were observed in vivo under laboratory conditions and in the plant rhizosphere.</jats:p>