Crystallographic studies on snRNP-and SMN-Associated DExD/H-box proteins and on the editosome-specific nuclease TbMP42

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The determination of the three-dimensional structures of protein-RNA complexes involved in mRNA maturation is a prerequiste for an understanding of their molecular function. We propose crystallographic studies on several DExD/H box proteins associated with snRNP or SMN particles as well as on a nuclease of the editosome from T. brucei. The DExD/H box proteins belong to the family of ATP-dependent helicases and exhibit an NTPase activity stimulated by dsRNA. Only a few DExD/H proteins have actually been show n to unwind dsRNA, and their activity and/or specificity might dependent on other proteins. Besides the conserved helicase domain, many DExD/H proteins contain additional domains, which are important for the interaction with other proteins and might affect the specificity and catalytic activity. Some DExD/H proteins can also disrupt protein-RNA complexes or affect the folding of RNA. At least eight DExD/H box proteins are required for the splicing of pre-mRNAs. We will focus on the crystal structure analysi s of the snRNP-associated DExD/H box proteins U5-100K (Prp28p), Prp22p and UAP56 (Sub2p), all required for pre-mRNA splicing, and of the DExD/H protein Gemin3 (Dp103), which is part of the SMN-complex involved in snRNP biogenesis. We will also determine the crystal structure of the novel nuclease TbMP42, which is involved in mRNA editing. All these crystallographic studies will preferably address the structures of functional protein-RNA or protein-protein complexes. The projects are carried out in collabora tion with the groups of Lührmann, Fischer and Göringer.