title: Hybrid Approaches to Structural Characterization of Conformational Ensembles of Complex Macromolecular Systems Combining NMR Residual Dipolar Couplings and Solution X-ray Scattering.
abstract: Solving structures or structural ensembles of large macromolecular systems in solution poses a challenging problem. While NMR provides structural information at atomic resolution, increased spectral complexity, chemical shift overlap, and short transverse relaxation times (associated with slow tumbling) render application of the usual techniques that have been so successful for medium sized systems (<50 kDa) difficult. Solution X-ray scattering, on the other hand, is not limited by molecular weight but only provides low resolution structural information related to the overall shape and size of the system under investigation. Here we review how combining atomic resolution structures of smaller domains with sparse experimental data afforded by NMR residual dipolar couplings (which yield both orientational and shape information) and solution X-ray scattering data in rigid-body simulated annealing calculations provides a powerful approach for investigating the structural aspects of conformational dynamics in large multidomain proteins. The application of this hybrid methodology is illustrated for the 128 kDa dimer of bacterial Enzyme I which exists in a variety of open and closed states that are sampled at various points in the catalytic cycles, and for the capsid protein of the human immunodeficiency virus.
authors.affiliation: Department of Chemistry, Iowa State University , Ames, Iowa 50011, United States.|Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University , Ames, Iowa 50011, United States.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Venditti
authors.affiliation: Department of Chemistry, Iowa State University , Ames, Iowa 50011, United States.
authors.forename: Timothy K
authors.initials: TK
authors.lastname: Egner
authors.affiliation: Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health , Bethesda, Maryland 20892-0520, United States.
authors.forename: G Marius
authors.initials: GM
authors.lastname: Clore
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D036022:Capsid Proteins / Q000737:chemistry / Q000378:metabolism; D015497:HIV-1 / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D053838:Scattering, Small Angle; D014961:X-Ray Diffraction
chemical_list: D001426:Bacterial Proteins; D036022:Capsid Proteins; D011506:Proteins