C-Terminal Moiety of Tudor Contains Its In Vivo Activity in Drosophila

Abstract

BackgroundIn early Drosophila embryos, the germ plasm is localized to the posterior pole region and is partitioned into the germline progenitors, known as pole cells. Germ plasm, or pole plasm, contains the polar granules which form during oogenesis and are required for germline development. Components of these granules are also present in the perinuclear region of the nurse cells, the nuage. One such component is Tudor (Tud) which is a large protein containing multiple Tudor domains. It was previously reported that specific Tudor domains are required for germ cell formation and Tud localization.Methodology/Principal FindingsIn order to better understand the function of Tud the distribution and functional activity of fragments of Tud were analyzed. These fragments were fused to GFP and the fusion proteins were synthesized during oogenesis. Non-overlapping fragments of Tud were found to be able to localize to both the nuage and pole plasm. By introducing these fragments into a tud mutant background and testing their ability to rescue the tud phenotype, I determined that the C-terminal moiety contains the functional activity of Tud. Dividing this fragment into two parts reduces its localization in pole plasm and abolishes its activity.Conclusions/SignificanceI conclude that the C-terminal moiety of Tud contains all the information necessary for its localization in the nuage and pole plasm and its pole cell-forming activity. The present results challenge published data and may help refining the functional features of Tud.

Structure and domain organization of Drosophila Tudor

“…The sDMA-dependent interaction between Tud and Aub is part of a broad range of phenomena involving tudor domain and Piwi family proteins, in species ranging from fruit flies to mammals 3 . We and others have shown previously that domains 7-11 of Tud (Tud7-11) were necessary and sufficient for germ cell formation and interaction with arginine-methylated Aub 9 , 10 , 11 . The structure of Tud11 in complex with sDMA-Aub peptides, together with the structure of human SND1 (TDRD11) bound to sDMA peptides from PIWIL1, uncovered the composition of the sDMA-binding pocket, which consists of a cage of four aromatic residues and an asparagine 10 , 12 .…”