New Kids on the Block: Self-synthesizing Dna Transposons

Motivation: Transposable elements constitute quite significant static and dynamic components of eukaryotic genomes. Moreover, transposable elements serve as efficient tools in genetic engineering. Therefore, identification and studies of transposable elements are important for researchers working in different fields of molecular biology. Results: Based on computational studies of eukaryotic genomes, we discovered a novel class of DNA transposons, called Polintons, characterized by a unique set of proteins including a protein-primed family B DNA polymerase, retroviral integrase, cysteine protease, and ATPase. Polintons are also characterized by 6-bp target site duplications, long terminal inverted repeats, and 5′-AG and TC-3′ termini. According to a transposition model discussed here, a Polinton DNA molecule excised from the genome by the Polinton-encoded integrase serves as a template for extrachromosomal synthesis of its double-stranded DNA copy by the Polinton-encoded DNA polymerase and is inserted into genome by the integrase. Availability: http://www.girinst.org/repbase/.