1f78
|
SOLUTION STRUCTURE OF RNASE P RNA (M1 RNA) P4 STEM OLIGORIBONUCLEOTIDE COMPLEXED WITH COBALT (III) HEXAMINE, NMR, MINIMIZED AVERAGE STRUCTURE
OverviewOverview
We determined the solution structure of two 27-nt RNA hairpins and their, complexes with cobalt(III)-hexammine (Co(NH3)3+(6)) by NMR spectroscopy., The RNA hairpins used in this study are the P4 region from Escherichia, coli RNase P RNA and a C-to-U mutant that confers altered divalent, metal-ion specificity (Ca2+ replaces Mg2+) for catalytic activity of this, ribozyme. Co(NH3)3+(6) is a useful spectroscopic probe for, Mg(H2O)2+(6)-binding sites because both complexes have octahedral symmetry, and have similar radii. The thermodynamics of binding to both RNA hairpins, was studied using chemical shift changes upon titration with Mg2+, Ca2+, and Co(NH3)3+(6). We found that the equilibrium binding constants for each, of the metal ions was essentially unchanged when the P4 model RNA hairpin, was mutated, although the NMR structures show that the RNA hairpins adopt, different conformations. In the C-to-U mutant a C.G base pair is replaced, by U.G, and the conserved bulged uridine in the P4 wild-type stem shifts, in the 3' direction by 1 nt. Intermolecular NOE cross-peaks between, Co(NH3)3+(6) and RNA protons were used to locate the site of Co(NH3)3+(6), binding to both RNA hairpins. The metal ion binds in the major groove near, a bulge loop, but is shifted 5' by more than 1 bp in the mutant. The, change of the metal-ion binding site provides a possible explanation for, changes in catalytic activity of the mutant RNase P in the presence of, Ca2+.
About this StructureAbout this Structure
1F78 is a Protein complex structure of sequences from [1] with NCO as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Solution structure and metal-ion binding of the P4 element from bacterial RNase P RNA., Schmitz M, Tinoco I Jr, RNA. 2000 Sep;6(9):1212-25. PMID:10999599
Page seeded by OCA on Sat Nov 24 23:24:41 2007