ABSTRACT: Eukaryotes contain numerous transposable or mobile elements capable of parasite-like proliferation in the host genome. All known transposable elements in eukaryotes belong to two types: retrotransposons and DNA transposons. Here we report a previously uncharacterized class of DNA transposons called Polintons that populate genomes of protists, fungi, and animals, including entamoeba, soybean rust, hydra, sea anemone, nematodes, fruit flies, beetle, sea urchin, sea squirt, fish, lizard, frog, and chicken. Polintons from all these species are characterized by a unique set of proteins necessary for their transposition, including a protein-primed DNA polymerase B, retroviral integrase, cysteine protease, and ATPase. In addition, Polintons are characterized by 6-bp target site duplications, term
