Core 2: Crystallography - Summary The CRNA Crystallography Core will collaborate with CRNA investigators to solve crystal structures of RNA-protein complexes, RNAs and proteins relevant to HIV RNA- mediated processes. The Core also provides essential expertise and materials that extend far beyond the crystallography mission and support many macromolecule preparation and analysis aspects of CRNA research. The Core team, led by Smith and Stuckey, offers collaborative expertise in molecular biology tailored for RNAs and RNA- protein complexes, including construct design, expression testing, and development of purification protocols. The resulting vectors, expression plasmids and protocols as well as purified RNAs, RNA-protein complexes and proteins are provided to collaborating investigators in the CRNA, with the Core lab at the University of Michigan acting as a repository for materials and protocols. Two new members of the Crystallography Core team, CRNA investigator Pornillos (U Virginia) and Significant Contributor Zhang (NIDDK, NIH), bring exceptional expertise in the design, production and validation of RNAs and RNA-protein complexes, particularly for crystallization. In CRNA 2.0, the Core will develop novel methods for expression of RNAs, formation of RNA-protein complexes by co-expression, and design of chaperones to aid RNA crystallization. The Core will also establish an in vitro RNA synthesis capability at Michigan. In support of its crystallography mission, the Core will develop cutting-edge methods to aid RNA crystallization, to improve the diffraction quality of crystals, to solve the phase problem for RNA-containing crystals, to improve crystallographic refinement for RNA-containing structures, and to facilitate the combination of crystallography and electron microscopy. !