title: Major groove width variations in RNA structures determined by NMR and impact of 13C residual chemical shift anisotropy and 1H-13C residual dipolar coupling on refinement.
abstract: Ribonucleic acid structure determination by NMR spectroscopy relies primarily on local structural restraints provided by (1)H- (1)H NOEs and J-couplings. When employed loosely, these restraints are broadly compatible with A- and B-like helical geometries and give rise to calculated structures that are highly sensitive to the force fields employed during refinement. A survey of recently reported NMR structures reveals significant variations in helical parameters, particularly the major groove width. Although helical parameters observed in high-resolution X-ray crystal structures of isolated A-form RNA helices are sensitive to crystal packing effects, variations among the published X-ray structures are significantly smaller than those observed in NMR structures. Here we show that restraints derived from aromatic (1)H- (13)C residual dipolar couplings (RDCs) and residual chemical shift anisotropies (RCSAs) can overcome NMR restraint and force field deficiencies and afford structures with helical properties similar to those observed in high-resolution X-ray structures.
authors.affiliation: Howard Hughes Medical Institute and Department of Chemistry and Biochemistry, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
authors.forename: Blanton S
authors.initials: BS
authors.lastname: Tolbert
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Miyazaki
authors.forename: Shawn
authors.initials: S
authors.lastname: Barton
authors.forename: Benyam
authors.initials: B
authors.lastname: Kinde
authors.forename: Patrice
authors.initials: P
authors.lastname: Starck
authors.forename: Rashmi
authors.initials: R
authors.lastname: Singh
authors.forename: Ad
authors.initials: A
authors.lastname: Bax
authors.forename: David A
authors.initials: DA
authors.lastname: Case
authors.forename: Michael F
authors.initials: MF
authors.lastname: Summers
mesh_terms: D016880:Anisotropy; D002247:Carbon Isotopes / Q000737:chemistry*; D018360:Crystallography, X-Ray; D030561:Databases, Nucleic Acid; D056004:Molecular Dynamics Simulation; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D009690:Nucleic Acid Conformation; D012313:RNA / Q000737:chemistry*
chemical_list: D002247:Carbon Isotopes; D012313:RNA