title: How to tackle protein structural data from solution and solid state: An integrated approach.
abstract: Long-range NMR restraints, such as diamagnetic residual dipolar couplings and paramagnetic data, can be used to determine 3D structures of macromolecules. They are also used to monitor, and potentially to improve, the accuracy of a macromolecular structure in solution by validating or "correcting" a crystal model. Since crystal structures suffer from crystal packing forces they may not be accurate models for the macromolecular structures in solution. However, the presence of real differences should be tested for by simultaneous refinement of the structure using both crystal and solution NMR data. To achieve this, the program REFMAC5 from CCP4 was modified to allow the simultaneous use of X-ray crystallographic and paramagnetic NMR data and/or diamagnetic residual dipolar couplings. Inconsistencies between crystal structures and solution NMR data, if any, may be due either to structural rearrangements occurring on passing from the solution to solid state, or to a greater degree of conformational heterogeneity in solution with respect to the crystal. In the case of multidomain proteins, paramagnetic restraints can provide the correct mutual orientations and positions of domains in solution, as well as information on the conformational variability experienced by the macromolecule.
authors.affiliation: Magnetic Resonance Center (CERM) and Department of Chemistry "Ugo Schiff", University of Florence, Italy(1). Electronic address: carlon@cerm.unifi.it.
authors.forename: Azzurra
authors.initials: A
authors.lastname: Carlon
authors.affiliation: Magnetic Resonance Center (CERM) and Department of Chemistry "Ugo Schiff", University of Florence, Italy(1). Electronic address: ravera@cerm.unifi.it.
authors.forename: Enrico
authors.initials: E
authors.lastname: Ravera
authors.affiliation: Magnetic Resonance Center (CERM) and Department of Chemistry "Ugo Schiff", University of Florence, Italy(1). Electronic address: andralojc@cerm.unifi.it.
authors.forename: Witold
authors.initials: W
authors.lastname: Andrałojć
authors.affiliation: Magnetic Resonance Center (CERM) and Department of Chemistry "Ugo Schiff", University of Florence, Italy(1). Electronic address: parigi@cerm.unifi.it.
authors.forename: Giacomo
authors.initials: G
authors.lastname: Parigi
authors.affiliation: MRC Laboratory for Molecular Biology, Francis Crick Ave, Cambridge CB2 0QH, UK. Electronic address: garib@mrc-lmb.cam.ac.uk.
authors.forename: Garib N
authors.initials: GN
authors.lastname: Murshudov
authors.affiliation: Magnetic Resonance Center (CERM) and Department of Chemistry "Ugo Schiff", University of Florence, Italy(1). Electronic address: claudioluchinat@cerm.unifi.it.
authors.forename: Claudio
authors.initials: C
authors.lastname: Luchinat
mesh_terms: D018360:Crystallography, X-Ray / Q000379:methods*; D006801:Humans; D008958:Models, Molecular; D046912:Multiprotein Complexes / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D000072417:Protein Domains; D011506:Proteins / Q000737:chemistry*
chemical_list: D046912:Multiprotein Complexes; D011506:Proteins
keywords: Integrated structural biology; Paramagnetic restraints; Pseudo-contact shifts; Residual dipolar couplings; Structural refinement