A novel paramagnetic relaxation enhancement tag for nucleic acids: a tool to study structure and dynamics of RNA.
In this work, we present a novel 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) radical phosphoramidite building block, which can be attached to the 5'-terminus of nucleic acids. To investigate the paramagnetic relaxation enhancement (PRE) emanating from this radical center, we incorporated the TEMPO label into various types of RNAs. We measured proton PREs for selectively (13)C-isotope labeled nucleotides to derive long-range distance restraints in a short 15 nucleotide stem-loop model system, underscoring the potential of the 5'-TEMPO tag to determine long-range distance restraints for solution structure determination. We subsequently applied the distance-dependent relaxation enhancement induced by the nitroxide radical to discern two folding states in a bistable RNA. Finally, we investigated the fast conformational sampling of the HIV-1 TAR RNA, a paradigm for structural flexibility in nucleic acids. With PRE NMR in combination with molecular dynamics simulations, the structural plasticity of this RNA was analyzed in the absence and presence of the ligand L-argininamide.
Institute of Organic Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck , Innrain 80/82, 6020 Innsbruck, Austria.
Christoph H
CH
Wunderlich
Roland G
RG
Huber
Romana
R
Spitzer
Klaus R
KR
Liedl
Karin
K
Kloiber
Christoph
C
Kreutz
D001120:Arginine / Q000031:analogs & derivatives / Q000737:chemistry; D002247:Carbon Isotopes; D003497:Cyclic N-Oxides / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D016325:HIV Long Terminal Repeat; D055029:Inverted Repeat Sequences; D008024:Ligands; D056004:Molecular Dynamics Simulation; D009589:Nitrogen Oxides / Q000737:chemistry; D009690:Nucleic Acid Conformation; D009943:Organophosphorus Compounds / Q000737:chemistry*; D011522:Protons; D012313:RNA / Q000737:chemistry*; D013113:Spin Labels; D013194:Staining and Labeling / Q000379:methods*
D002247:Carbon Isotopes; D003497:Cyclic N-Oxides; D008024:Ligands; D009589:Nitrogen Oxides; D009943:Organophosphorus Compounds; D011522:Protons; D013113:Spin Labels; C434331:phosphoramidite; C069339:argininamide; D012313:RNA; D001120:Arginine; C039900:nitroxyl; C003959:TEMPO