Identification of a mosaic transposable element ofParacoccus marcusiicomposed of insertion sequence ISPmar4(ISAs1family) and an IS1247a-driven transposable module (TMo)

A sacB-based trap plasmid was used to clone a mosaic transposable element (TE) in the carotenoid producer Paracoccus marcusii OS22. This element is composed of an insertion sequence (IS) ISPmar4 (ISAs1 family), which contains an inserted functional transposable module (TMo) generated by a copy of IS1247a (of the IS1380 family). Besides IS1247a sequences, the TMo also contains the 3'-end region of a putative alpha/beta hydrolase gene, whose expression might be activated from the P(2) promoter of IS1247a. The identification of this novel TE provides evidence that transposition of TMos may change an IS into a more complex element resembling noncomposite transposons.