Core 2. Crystallography Summary The CRNA Crystallography Core will collaborate with CRNA investigators to solve crystal structures of RNA- protein complexes, RNAs and proteins. A key activity of the Core is to provide expertise in molecular biology tailored for RNAs and RNA-protein complexes, including construct design, expression testing, and development of purification protocols, and in biophysical characterization of purified macromolecules and complexes. These contributions in molecular biology and biophysics are not only critical to the crystallography focus of the Core, but are also available to CRNA Projects as needed for production and characterization of proteins or RNA-protein complexes. The Core will also provide construct designs, expression plasmids and protocols as well as purified proteins, RNAs and RNA-protein complexes to CRNA labs. The Core lab at the University of Michigan will serve as a repository for materials and protocols. The Core team is co-led by PIs Janet Smith (University of Michigan) and Jinwei Zhang (NIDDK, NIH), who brings expertise in the design of RNAs and RNA-protein complexes for crystallization. The Core team will focus on three aims. The Core will develop or adapt cutting-edge methods for RNA designs to facilitate expression, RNA-protein co-expression, crystallization chaperones for RNA, and establishment of an in vitro RNA synthesis capability. In support of its crystallography mission, the Core will develop cutting-edge methods to aid RNA crystallization, to improve the diffraction quality and 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.