title: The use of dipolar couplings for determining the solution structure of rat apo-S100B(betabeta).
abstract: The relative orientations of adjacent structural elements without many well-defined NOE contacts between them are typically poorly defined in NMR structures. For apo-S100B(betabeta) and the structurally homologous protein calcyclin, the solution structures determined by conventional NMR exhibited considerable differences and made it impossible to draw unambiguous conclusions regarding the Ca2+-induced conformational change required for target protein binding. The structure of rat apo-S100B(betabeta) was recalculated using a large number of constraints derived from dipolar couplings that were measured in a dilute liquid crystalline phase. The dipolar couplings orient bond vectors relative to a single-axis system, and thereby remove much of the uncertainty in NOE-based structures. The structure of apo-S100B(betabeta) indicates a minimal change in the first, pseudo-EF-hand Ca2+ binding site, but a large reorientation of helix 3 in the second, classical EF-hand upon Ca2+ binding.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore 21201, USA.
authors.forename: A C
authors.initials: AC
authors.lastname: Drohat
authors.forename: N
authors.initials: N
authors.lastname: Tjandra
authors.forename: D M
authors.initials: DM
authors.lastname: Baldisseri
authors.forename: D J
authors.initials: DJ
authors.lastname: Weber
mesh_terms: D000818:Animals; D002135:Calcium-Binding Proteins / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D009414:Nerve Growth Factors / Q000737:chemistry*; D017433:Protein Structure, Secondary; D051381:Rats; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; D017386:Sequence Homology, Amino Acid; D013223:Statistics as Topic
chemical_list: D002135:Calcium-Binding Proteins; D009414:Nerve Growth Factors; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; C579158:S100b protein, rat