2mtk | pdb_00002mtk
NMR structure of the III-IV-V three-way junction from the VS ribozyme and identification of magnesium-binding sites using paramagnetic relaxation enhancement
Structural highlights
Publication Abstract from PubMedThe VS ribozyme is a catalytic RNA found within some natural isolates of Neurospora that is being used as a model system to improve our understanding of RNA structure, catalysis, and engineering. The catalytic domain contains five helical domains (SLII-SLVI) that are organized by two three-way junctions. The III-IV-V junction is required for high-affinity binding of the substrate domain (SLI) through formation of a kissing loop interaction with SLV. Here, we determine the high-resolution nuclear magnetic resonance (NMR) structure of a 47-nucleotide RNA containing the III-IV-V junction (J345). The J345 RNA adopts a Y-shaped fold typical of the family C three-way junctions, with coaxial stacking between stems III and IV and an acute angle between stems III and V. The NMR structure reveals that the core of the III-IV-V junction contains four stacked base triples, a U-turn motif, a cross-strand stacking interaction, an A-minor interaction, and a ribose zipper. In addition, the NMR structure shows that the cCUUGg tetraloop used to stabilize stem IV adopts a novel RNA tetraloop fold, different from the known gCUUGc tetraloop structure. Using Mn(2+)-induced paramagnetic relaxation enhancement, we identify six Mg(2+)-binding sites within J345, including one associated with the cCUUGg tetraloop and two with the junction core. The NMR structure of J345 likely represents the conformation of the III-IV-V junction in the context of the active VS ribozyme and suggests that this junction functions as a dynamic hinge that contributes to substrate recognition and catalysis. Moreover, this study highlights a new role for family C three-way junctions in long-range tertiary interactions. Nuclear Magnetic Resonance Structure of the III-IV-V Three-Way Junction from the Varkud Satellite Ribozyme and Identification of Magnesium-Binding Sites Using Paramagnetic Relaxation Enhancement.,Bonneau E, Legault P Biochemistry. 2014 Oct 7;53(39):6264-75. doi: 10.1021/bi500826n. Epub 2014 Sep, 19. PMID:25238589[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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