Repression of retroelements in Drosophila germline via piRNA pathway by the Tudor domain protein Tejas.

The Piwi-interacting RNAs (piRNAs) have been shown to safeguard the animal germline genome against deleterious retroelements [1-9]. Many factors involved in the production of piRNAs localize to nuage, a unique perinuclear structure in animal germline cells [10], suggesting that nuage may function as a site for processing of germline piRNAs [1, 3-6, 11-14]. Here we report a conserved yet uncharacterized component of the germline piRNA pathway, Tejas (Tej), which localizes to nuage. tej is required for the repression of some retroelements and for the production of sufficient germline piRNAs. The localization of Tej to nuage depends on vasa (vas) [15] and spindle-E (spn-E) [1, 16, 17] while it regulates the localization of Spn-E, Aubergine (Aub) [3, 4, 14], Argonaute3 (Ago3) [5], Krimper (Krimp) [13], and Maelstrom (Mael) [18] to nuage. Aub, Vas, and Spn-E physically interact with Tej through the N terminus containing the conserved tejas domain, which is necessary and sufficient for its germline function. Aub and Spn-E also bind to the tudor domain at the C terminus. Our data suggest that Tej contributes to the formation of a macromolecular complex at perinuclear region and engages it in the production of germline piRNAs.