title: Measurement of imino 1H-1H residual dipolar couplings in RNA.
abstract: Imino (1)H-(15)N residual dipolar couplings (RDCs) provide additional structural information that complements standard (1)H-(1)H NOEs leading to improvements in both the local and global structure of RNAs. Here, we report measurement of imino (1)H-(1)H RDCs for the Iron Responsive Element (IRE) RNA and native E. coli tRNA(Val) using a BEST-Jcomp-HMQC2 experiment. (1)H-(1)H RDCs are observed between the imino protons in G-U wobble base pairs and between imino protons on neighboring base pairs in both RNAs. These imino (1)H-(1)H RDCs complement standard (1)H-(15)N RDCs because the (1)H-(1)H vectors generally point along the helical axis, roughly perpendicular to (1)H-(15)N RDCs. The use of longitudinal relaxation enhancement increased the signal-to-noise of the spectra by ~3.5-fold over the standard experiment. The ability to measure imino (1)H-(1)H RDCs offers a new restraint, which can be used in NMR domain orientation and structural studies of RNAs.
authors.affiliation: Department of Chemistry and Biochemistry, 215 UCB, University of Colorado, Boulder, CO 80309-0215, USA.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Latham
authors.forename: Arthur
authors.initials: A
authors.lastname: Pardi
mesh_terms: D004926:Escherichia coli; D007097:Imines / Q000737:chemistry*; D035925:Iron-Regulatory Proteins / Q000235:genetics; D009587:Nitrogen Isotopes / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D012313:RNA / Q000737:chemistry*; D012329:RNA, Bacterial / Q000737:chemistry*; D012366:RNA, Transfer, Val / Q000737:chemistry*
chemical_list: D007097:Imines; D035925:Iron-Regulatory Proteins; D009587:Nitrogen Isotopes; D012329:RNA, Bacterial; D012366:RNA, Transfer, Val; D012313:RNA