title: Integrated analysis of the conformation of a protein-linked spin label by crystallography, EPR and NMR spectroscopy.
abstract: Long-range structural information derived from paramagnetic relaxation enhancement observed in the presence of a paramagnetic nitroxide radical is highly useful for structural characterization of globular, modular and intrinsically disordered proteins, as well as protein-protein and protein-DNA complexes. Here we characterized the conformation of a spin-label attached to the homodimeric protein CylR2 using a combination of X-ray crystallography, electron paramagnetic resonance (EPR) and NMR spectroscopy. Close agreement was found between the conformation of the spin label observed in the crystal structure with interspin distances measured by EPR and signal broadening in NMR spectra, suggesting that the conformation seen in the crystal structure is also preferred in solution. In contrast, conformations of the spin label observed in crystal structures of T4 lysozyme are not in agreement with the paramagnetic relaxation enhancement observed for spin-labeled CylR2 in solution. Our data demonstrate that accurate positioning of the paramagnetic center is essential for high-resolution structure determination.
authors.affiliation: Department of Structural Chemistry, University of Göttingen, Tammannstraße 4, 37077, Göttingen, Germany.
authors.forename: Tim
authors.initials: T
authors.lastname: Gruene
authors.forename: Min-Kyu
authors.initials: MK
authors.lastname: Cho
authors.forename: Irina
authors.initials: I
authors.lastname: Karyagina
authors.forename: Hai-Young
authors.initials: HY
authors.lastname: Kim
authors.forename: Christian
authors.initials: C
authors.lastname: Grosse
authors.forename: Karin
authors.initials: K
authors.lastname: Giller
authors.forename: Markus
authors.initials: M
authors.lastname: Zweckstetter
authors.forename: Stefan
authors.initials: S
authors.lastname: Becker
mesh_terms: D018360:Crystallography, X-Ray / Q000379:methods*; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D011506:Proteins / Q000737:chemistry*; D013113:Spin Labels
chemical_list: D011506:Proteins; D013113:Spin Labels