1yn2
|
Solution structure of the Neurospora VS ribozyme stem-loop V in the presence of MgCl2 with modeling of bound manganese ions
OverviewOverview
In the Neurospora VS ribozyme, magnesium ions facilitate formation of a, loop-loop interaction between stem-loops I and V, which is important for, recognition and activation of the stem-loop I substrate. Here, we present, the high-resolution NMR structure of stem-loop V (SL5) in the presence of, Mg(2+) (SL5(Mg)) and demonstrate that Mg(2+) induces a conformational, change in which the SL5 loop adopts a compact structure with most, characteristics of canonical U-turn structures. Divalent cation-binding, sites were probed with Mn(2+)-induced paramagnetic line broadening and, intermolecular NOEs to Co(NH(3))(6)(3+). Structural modeling of, Mn(H(2)O)(6)(2+) in SL5(Mg) revealed four divalent cation-binding sites in, the loop. Sites 1, 3, and 4 are located in the major groove near multiple, phosphate groups, whereas site 2 is adjacent to N7 of G697 and N7 of A698, in the minor groove. Cation-binding sites equivalent to sites 1-3 in SL5, are present in other U-turn motifs, and these metal-binding sites may, represent a common feature of the U-turn fold. Although magnesium ions, affect the loop conformation, they do not significantly change the, conformation of residues 697-699 involved in the proposed Watson-Crick, base pairs with stem-loop I. In both the presence and the absence of, Mg(2+), G697, A698, and C699 adopt an A-form structure that exposes their, Watson-Crick faces, and this is compatible with their proposed interaction, with stem-loop I. In SL5(Mg), however, U700 becomes exposed on the minor, groove face of the loop in the proximity of the bases of G697, A698, and, C699, suggesting that the Mg(2+)-bound conformation of stem-loop V allows, additional contacts with stem-loop I. These studies improve our, understanding of the role of Mg(2+) in U-turn structures and in substrate, recognition by the VS ribozyme.
About this StructureAbout this Structure
1YN2 is a Protein complex structure of sequences from [1] with MN as ligand. Full crystallographic information is available from OCA.
ReferenceReference
NMR structure of varkud satellite ribozyme stem-loop V in the presence of magnesium ions and localization of metal-binding sites., Campbell DO, Bouchard P, Desjardins G, Legault P, Biochemistry. 2006 Sep 5;45(35):10591-605. PMID:16939211
Page seeded by OCA on Sun Nov 25 04:23:01 2007