Activity of zebrafish THAP9 transposase and zebrafish P element-like transposons.

Transposable elements are mobile DNA segments that are found ubiquitously across the three domains of life. One family of transposons, called P elements, were discovered in the fruit fly . Since their discovery, P element transposase-homologous genes (called THAP-domain containing 9 or THAP9) have been discovered in other animal genomes. Here, we show that the zebrafish () genome contains both an active THAP9 transposase (zfTHAP9) and mobile P-like transposable elements (called ). zfTHAP9 transposase can excise one of its own elements (2) and P elements. P element transposase (DmTNP) is also able to excise the zebrafish 2 element, even though it's distinct from the P element. However, zfTHAP9 cannot transpose 2 or P elements, indicating partial transposase activity. Characterization of the N-terminal THAP DNA binding domain of zfTHAP9 shows distinct DNA binding site preferences from DmTNP and mutation of the zfTHAP9, based on known mutations in DmTNP, generated a hyperactive protein,. These results define an active vertebrate THAP9 transposase that can act on the endogenous zebrafish and P elements.