title: Fusion RNAs in crystallographic studies of double-stranded RNA from trypanosome RNA editing.
abstract: Head-to-head fusions of two identical double-stranded fragments of RNA can be designed to self-assemble from a single RNA species and form a double-stranded helix with a twofold rotation axis relating the two strands. These symmetrical RNA molecules are more likely to crystallize without end-on-end statistical packing disorder because the two halves of the molecule are identical. This approach can be used to study many fragments of double-stranded RNA or many isolated helical domains from large single-stranded RNAs that may not yet be amenable to high-resolution studies by crystallography or NMR. We used fusion RNAs to study one (the U-helix) of three functional domains formed when guide RNA binds to its cognate pre-edited mRNA from the trypanosome RNA editing system. The U-helix forms when the 3' oligo(U) tail of the guide RNA (gRNA) binds to the purine-rich, pre-edited mRNA upstream from the current RNA editing site. Fusion RNAs 16-and 32-base pairs in length formed crystals that gave diffraction to 1.37 and 1.05 Å respectively. We provide the composition of a fusion RNA crystallization screen and describe the X-ray data collection, structure determination, and refinement of the crystal structures of fusion RNAs.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, 975 NE 10th St., Stanton L. Young Biomedical Research Center Rm. 466, Oklahoma City, OK, 73104-5419, USA, blaine-mooers@ouhsc.edu.
authors.forename: Blaine H M
authors.initials: BH
authors.lastname: Mooers
mesh_terms: D018360:Crystallography, X-Ray / Q000379:methods*; D009690:Nucleic Acid Conformation; D017393:RNA Editing / Q000235:genetics*; D012330:RNA, Double-Stranded / Q000737:chemistry*; D016053:RNA, Protozoan / Q000737:chemistry*; D015203:Reproducibility of Results; D014345:Trypanosoma / Q000235:genetics*
chemical_list: D012330:RNA, Double-Stranded; D016053:RNA, Protozoan