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ABSTRACT: Solid-state NMR spectroscopy proved to be a versatile tool for characterization of structure and dynamics of complex biochemical systems. In particular, magic angle spinning (MAS) solid-state NMR came to maturity for application towards structural elucidation of biological macromolecules. Current challenges in applying solid-state NMR as well as progress achieved recently will be discussed in the following chapter focusing on conceptual aspects important for structural elucidation of proteins.
Topics in current chemistry 03/2013; · 4.29 Impact Factor
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Robert Schneider,
Miria C Schumacher,
Henrik Mueller,
Deepak Nand,
Volker Klaukien, Henrike Heise,
Dietmar Riedel,
Gerhard Wolf,
Elmar Behrmann,
Stefan Raunser,
Ralf Seidel,
Martin Engelhard,
Marc Baldus
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ABSTRACT: Protein aggregation via polyglutamine stretches occurs in a number of severe neurodegenerative diseases such as Huntington's disease. We have investigated fibrillar aggregates of polyglutamine peptides below, at, and above the toxicity limit of around 37 glutamine residues using solid-state NMR and electron microscopy. Experimental data are consistent with a dry fibril core of at least 70-80 Å in width for all constructs. Solid-state NMR dipolar correlation experiments reveal a largely β-strand character of all samples and point to tight interdigitation of hydrogen-bonded glutamine side chains from different sheets. Two approximately equally frequent populations of glutamine residues with distinct sets of chemical shifts are found, consistent with local backbone dihedral angles compensating for β-strand twist or with two distinct sets of side-chain conformations. Peptides comprising 15 glutamine residues are present as single extended β-strands. Data obtained for longer constructs are most compatible with a superpleated arrangement with individual molecules contributing β-strands to more than one sheet and an antiparallel assembly of strands within β-sheets.
Journal of Molecular Biology 09/2011; 412(1):121-36. · 4.00 Impact Factor
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Ashutosh Kumar, Henrike Heise,
Marcel J J Blommers,
Philipp Krastel,
Esther Schmitt,
Frank Petersen,
Siva Jeganathan,
Eva-Maria Mandelkow,
Teresa Carlomagno,
Christian Griesinger,
Marc Baldus
Angewandte Chemie International Edition 10/2010; 49(41):7504-7. · 13.45 Impact Factor
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Damla Pinar Karpinar,
Madhu Babu Gajula Balija,
Sebastian Kügler,
Felipe Opazo,
Nasrollah Rezaei-Ghaleh,
Nora Wender,
Hai-Young Kim,
Grit Taschenberger,
Björn H Falkenburger, Henrike Heise, [......],
Gerhard H Braus,
Karin Giller,
Stefan Becker,
Alf Herzig,
Marc Baldus,
Herbert Jäckle,
Stefan Eimer,
Jörg B Schulz,
Christian Griesinger,
Markus Zweckstetter
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ABSTRACT: The relation of alpha-synuclein (alphaS) aggregation to Parkinson's disease (PD) has long been recognized, but the mechanism of toxicity, the pathogenic species and its molecular properties are yet to be identified. To obtain insight into the function different aggregated alphaS species have in neurotoxicity in vivo, we generated alphaS variants by a structure-based rational design. Biophysical analysis revealed that the alphaS mutants have a reduced fibrillization propensity, but form increased amounts of soluble oligomers. To assess their biological response in vivo, we studied the effects of the biophysically defined pre-fibrillar alphaS mutants after expression in tissue culture cells, in mammalian neurons and in PD model organisms, such as Caenorhabditis elegans and Drosophila melanogaster. The results show a striking correlation between alphaS aggregates with impaired beta-structure, neuronal toxicity and behavioural defects, and they establish a tight link between the biophysical properties of multimeric alphaS species and their in vivo function.
The EMBO Journal 10/2009; 28(20):3256-68. · 9.20 Impact Factor
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ABSTRACT: Fibrils from the Parkinson's-disease-related A53T mutant of alpha-synuclein were investigated by solid-state NMR spectroscopy, electron microscopy, and atomic force microscopy. Sequential solid-state NMR resonance assignments were obtained for a large fraction of the fibril core. Experiments conducted above and below the freezing point suggest that the fibrils contain regions with increased mobility and structural elements different from beta-strand character, in addition to the rigid beta-sheet-rich core region. As in earlier studies on wild-type alpha-synuclein, the C-terminus was found to be flexible and unfolded, whereas the main core region was highly rigid and rich in beta-sheets. Compared to fibrils from wild-type alpha-synuclein, the well-ordered beta-sheet region extends to at least L38 and L100. These results demonstrate that a disease-related mutant of alpha-synuclein differs in both aggregation kinetics and fibril structure.
Journal of Molecular Biology 08/2008; 380(3):444-50. · 4.00 Impact Factor
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ABSTRACT: We demonstrate that short, medium and long-range constraints can be extracted from proton mediated, rare-spin detected correlation solid-state NMR experiments for the microcrystalline 10.4 x 2 kDa dimeric model protein Crh. Magnetization build-up curves from cross signals in NHHC and CHHC spectra deliver detailed information on side chain conformers and secondary structure for interactions between spin pairs. A large number of medium and long-range correlations can be observed in the spectra, and an analysis of the resolved signals reveals that the constraints cover the entire sequence, also including inter-monomer contacts between the two molecules forming the domain-swapped Crh dimer. Dynamic behavior is shown to have an impact on cross signals intensities, as indicated for mobile residues or regions by contacts predicted from the crystal structure, but absent in the spectra. Our work validates strategies involving proton distance measurements for large and complex proteins as the Crh dimer, and confirms the magnetization transfer properties previously described for small molecules in solid protein samples.
Journal of Biomolecular NMR 05/2008; 40(4):239-50. · 3.61 Impact Factor
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ChemBioChem 10/2007; 8(14):1671-4. · 3.94 Impact Factor
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ABSTRACT: Solid-state NMR has long been utilized to study biomolecular structure and dynamics ranging from applications to protein complexes
[1] and nucleotides [2] to membrane proteins [3–5] and protein fibrils [6]. In the case of macroscopically oriented membrane
peptides, solid-state NMR furthermore has provided structural constraints to assemble three-dimensional (3D) membrane protein
structures (see Ref. [7] for a recent review). Under magic angle spinning (MAS) [8], structural investigations were focused
for a long time on the determination of local structural parameters. Recently, substantial progress has been made in NMR methodology,
instrumentation, and sample preparation that now permits 3D molecular structure determination under MAS from one or a limited
set of NMR samples. These approaches will be discussed in the context of this chapter. The interested reader is also referred
to a series of recent review articles [9–11].
12/2005: pages 527-530;
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ABSTRACT: The 140-residue protein alpha-synuclein (AS) is able to form amyloid fibrils and as such is the main component of protein inclusions involved in Parkinson's disease. We have investigated the structure and dynamics of full-length AS fibrils by high-resolution solid-state NMR spectroscopy. Homonuclear and heteronuclear 2D and 3D spectra of fibrils grown from uniformly (13)C/(15)N-labeled AS and AS reverse-labeled for two of the most abundant amino acids, K and V, were analyzed. (13)C and (15)N signals exhibited linewidths of <0.7 ppm. Sequential assignments were obtained for 48 residues in the hydrophobic core region. We identified two different types of fibrils displaying chemical-shift differences of up to 13 ppm in the (15)N dimension and up to 5 ppm for backbone and side-chain (13)C chemical shifts. EM studies suggested that molecular structure is correlated with fibril morphology. Investigation of the secondary structure revealed that most amino acids of the core region belong to beta-strands with similar torsion angles in both conformations. Selection of regions with different mobility indicated the existence of monomers in the sample and allowed the identification of mobile segments of the protein within the fibril in the presence of monomeric protein. At least 35 C-terminal residues were mobile and lacked a defined secondary structure, whereas the N terminus was rigid starting from residue 22. Our findings agree well with the overall picture obtained with other methods and provide insight into the amyloid fibril structure and dynamics with residue-specific resolution.
Proceedings of the National Academy of Sciences 12/2005; 102(44):15871-6. · 9.68 Impact Factor
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ABSTRACT: Understanding of the effects of intermolecular interactions, molecular dynamics, and sample preparation on high-resolution magic-angle spinning NMR data is currently limited. Using the example of a uniformly [13C,15N]-labeled sample of ubiquitin, we discuss solid-state NMR methods tailored to the construction of 3D molecular structure and study the influence of solid-phase protein preparation on solid-state NMR spectra. A comparative analysis of 13C', 13Calpha, and 13Cbeta resonance frequencies suggests that 13C chemical-shift variations are most likely to occur in protein regions that exhibit an enhanced degree of molecular mobility. Our results can be refined by additional solid-state NMR techniques and serve as a reference for ongoing efforts to characterize the structure and dynamics of (membrane) proteins, protein complexes, and other biomolecules by high-resolution solid-state NMR.
ChemBioChem 10/2005; 6(9):1638-47. · 3.94 Impact Factor
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ABSTRACT: It is shown that molecular structure and dynamics of a uniformly labeled membrane protein can be studied under magic-angle-spinning conditions. For this purpose, dipolar recoupling experiments are combined with novel through-bond correlation schemes that probe mobile protein segments. These NMR schemes are demonstrated on a uniformly [13C,15N] variant of the 52-residue polypeptide phospholamban. When reconstituted in lipid bilayers, the NMR data are consistent with an alpha-helical trans-membrane segment and a cytoplasmic domain that exhibits a high degree of structural disorder.
Journal of the American Chemical Society 10/2005; 127(37):12965-74. · 9.91 Impact Factor
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ABSTRACT: An approach is introduced to characterize conformational ensembles of intrinsically unstructured peptides on the atomic level using two-dimensional solid-state NMR data and their combination with molecular dynamics simulations. For neurotensin, a peptide that binds with high affinity to a G-protein coupled receptor, this method permits the investigation of the changes in conformational preferences of a neurotransmitter transferred from a frozen aqueous solution via a lipid model phase to the receptor-bound form. The results speak against a conformational pre-organization of the ligand in detergents in which the receptor has been shown to be functional. Further extensions to the study of protein folding are possible.
Biophysical Journal 10/2005; 89(3):2113-20. · 3.65 Impact Factor
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ABSTRACT: Solid-state Nuclear Magnetic Resonance (NMR) provides a general method to study molecular structure and dynamics in a non-crystalline and insoluble environment. We discuss the latest methodological progress to construct 3D molecular structures from solid-state NMR data obtained under magic-angle-spinning conditions. As shown for the neurotensin/NTS-1 system, these methods can be readily applied to the investigation of ligand-binding to G-protein coupled receptors.
Archiv der Pharmazie 07/2005; 338(5-6):217-28. · 1.71 Impact Factor
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ABSTRACT: Two types of 3D MAS NMR experiments are introduced, which combine standard (NC,CC) transfer schemes with (1H,1H) mixing to simultaneously detect connectivities and structural constraints of uniformly 15N,13C-labeled proteins with high spectral resolution. The homonuclear CCHHC and CCC experiments are recorded with one double-quantum evolution dimension in order to avoid a cubic diagonal in the spectrum. Depending on the second transfer step, spin systems or proton-proton contacts can be determined with reduced spectral overlap. The heteronuclear NHHCC experiment encodes NH-HC proton-proton interactions, which are indicative for the backbone conformation of the protein. The third dimension facilitates the identification of the amino acid spin system. Experimental results on U-[15N,13C]valine and U-[15N,13C]ubiquitin demonstrate their usefulness for resonance assignments and for the determination of structural constraints. Furthermore, we give a detailed analysis of alternative multidimensional sampling schemes and their effect on sensitivity and resolution.
Journal of Magnetic Resonance 04/2005; 173(1):64-74. · 2.14 Impact Factor
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ABSTRACT: The magnetic interaction and spin transfer via phosphorus have been investigated for the tri-tert-butylaminoxyl para-substituted triphenylphosphine oxide. For this radical unit, the conjugation existing between the pi* orbital of the NO group and the phenyl pi orbitals leads to an efficient delocalization of the spin from the radical to the neighboring aromatic ring. This has been confirmed by using fluid solution high-resolution EPR and solid state MAS NMR spectroscopy. The spin densities located on the atoms of the molecule could be probed since (1)H, (13)C, (14)N, and (31)P are nuclei active in NMR and EPR, and lead to a precise spin distribution map for the triradical. The experimental investigations were completed by a DFT computational study. These techniques established in particular that spin density is located at the phosphorus (rho=-15x10(-3) au), that its sign is in line with the sign alternation principle and that its magnitude is in the order of that found on the aromatic C atoms of the molecule. Surprisingly, whereas the spin distribution scheme supports ferromagnetic interactions among the radical units, the magnetic behavior found for this molecule revealed a low-spin ground state characterized by an intramolecular exchange parameter of J=-7.55 cm(-1) as revealed by solid state susceptibility studies and low temperature EPR. The X-ray crystal structures solved at 293 and 30 K show the occurrence of a crystallographic transition resulting in an ordering of the molecular units at low temperature.
Chemistry 12/2004; 11(1):128-39. · 5.93 Impact Factor
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ABSTRACT: A nitronyl-nitroxide (NIT) biradical D-NIT2 linked by a single double bond has been engineered and investigated in the solid state by a combination of X-ray diffraction, magnetic susceptibility measurement, EPR, as well as solid-state (1)H and (13)C NMR spectroscopies, and experimental electron density distribution. All techniques reveal that a double bond is a very efficient coupling unit for exchange interactions between two radical moieties. Using a Bleaney-Bowers model dimer (H = -JS(1)S(2)), a singlet-triplet energy gap of J = -460 K was found with the singlet state being the ground state. This very strong intramolecular interaction was confirmed by EPR measurements in CH(2)Cl(2) solution (6 10(-4) M) or dispersed in a polymer matrix at low concentration. In keeping with these unusual interactions, solid-state NMR signals of the biradical were found to be considerably less shifted than those found for related monoradicals. Temperature-dependent solid-state (13)C NMR spectra of D-NIT2 confirmed the very strong intramolecular coupling constant (J = -504 K). The electron density distribution of D-NIT2 was measured by high resolution X-ray diffraction, which also revealed that this biradical is an ideally conjugated system. The in-depth characterization includes the deformation maps and the observed electron density ellipticities, which exhibit a pronounced sigma-pi character of the O-N-C=C-N-O cores in keeping with an efficient electronic delocalization along the alkene spacer.
Journal of the American Chemical Society 11/2004; 126(39):12604-13. · 9.91 Impact Factor
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ABSTRACT: Crystallization of ferrocene and ruthenocene substituted in the 1- and 1'-positions by two nitronyl nitroxide radicals gave the new crystal phases beta-1 (besides the known phase alpha-1), alpha-2, and beta-2 whose structures were determined by X-ray analysis. In beta-1 the radical moieties adopt transoid positions, whereas two different cisoid conformations are adopted by alpha-2 and beta-2. These conformations result from inter- and intramolecular hydrogen bonds, respectively. All compounds experience antiferromagnetic interactions, and J/k(B) values up to -7 K have been found by fitting the experimental magnetic susceptibilities to a modified Bleaney-Bowers equation. The solid diradicals alpha-1, beta-1, alpha-2, and beta-2 as well as the ferrocene 3, which was substituted by a unique nitronyl nitroxide, were investigated by (13)C and (1)H NMR spectroscopy with magic angle spinning. The carbon signals cover a range of 2000 ppm, and are well resolved such that the structure could be confirmed. Conversion of the signal shifts into spin densities disclosed the mechanisms by which spin delocalization from the nitronyl nitroxide substituents to the metallocene core occurs. The spin density distribution in alpha-1, beta-1, and 3 was also predicted by DFT calculations. There is good agreement between the experimental and theoretical trends of the spin delocalization. The magnetic interactions were discussed in the light of intramolecular spin transfer and its dependence on geometric constraints, demonstrating that the 1,1'-metallocenylene bridge is not a robust magnetic coupler.
Chemistry 04/2004; 10(6):1355-65. · 5.93 Impact Factor
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ABSTRACT: Solid state NMR sample preparation and resonance assignments of the U-[13C,15N] 2x10.4 kDa dimeric form of the regulatory protein Crh in microcrystalline, PEG precipitated form are presented. Intra- and interresidue correlations using dipolar polarization transfer methods led to nearly complete sequential assignments of the protein, and to 88% of all 15N, 13C chemical shifts. For several residues, the resonance assignments differ significantly from those reported for the monomeric form analyzed by solution state NMR. Dihedral angles obtained from a TALOS-based statistical analysis suggest that the microcrystalline arrangement of Crh must be similar to the domain-swapped dimeric structure of a single crystal form recently solved using X-ray crystallography. For a limited number of protein residues, a remarkable doubling of the observed NMR resonances is observed indicative of local static or dynamic conformational disorder. Our study reports resonance assignments for the largest protein investigated by solid state NMR so far and describes the conformational dimeric variant of Crh with previously unknown chemical shifts.
Journal of Biomolecular NMR 01/2004; 27(4):323-39. · 3.61 Impact Factor
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ABSTRACT: Solid-state NMR provides unique possibilities to study insoluble or noncrystalline molecules at the atomic level. High-resolution conditions can be established by employing magic-angle spinning at ultrahigh magnetic fields. We discuss NMR methods that make use of these experimental improvements and allow for the study of multiply or uniformly [(13)C,(15)N]-labeled polypeptides and proteins. Recent biophysical applications are reviewed.
Accounts of Chemical Research 12/2003; 36(11):858-65. · 21.64 Impact Factor
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ABSTRACT: To shed light on the interaction in molecule-based magnetic materials, the decamethylmetallocenium hexafluorophosphates, [(C(5)Me(5))(2)M](+) [PF(6)](-) with M = Cr, Mn, Fe, Co, and Ni, as well as the tetracyanoethenides, [(C(5)Me(5))(2)M](+) [TCNE](-) with M = Cr, Mn, Fe, and Co, have been investigated in the solid state by using (1)H, (13)C, (19)F, and (31)P NMR spectroscopy under magic angle spinning (MAS). The isotropic (13)C and (1)H NMR signals cover ranges of about 1300 and 500 ppm, respectively. From the shift anisotropies of the ring carbon signal of the [(C(5)Me(5))(2)M](+) cations, the total unpaired electron spin density in the ligand pi orbitals has been calculated; it amounts up to 36% (M = Ni) and is negative for M = Cr, Mn, and Fe. The radical anion of [(C(5)Me(5))(2)M](+) [TCNE](-) shifts the (13)C NMR signals of all [(C(5)Me(5))(2)M](+) cations to high frequency, which establishes transfer of positive spin density from the anions to the cations. The (19)F and (31)P NMR signals of the paramagnetic salts [(C(5)Me(5))(2)M](+) [PF(6)](-) are shifted up to 13.5 ppm relative to diamagnetic [(C(5)Me(5))(2)Co](+) [PF(6)](-). The signs of these shifts are the same as those of the pi spin density in [(C(5)Me(5))(2)M](+). After consideration of interionic ligand- and metal-centered dipolar shifts, this establishes cation-anion spin delocalization. The mixed crystals [(C(5)Me(5))(2)M(x)Co(1-x)](+)[PF(6)](-) have been prepared for M = Cr and Ni. They are isostructural with [(C(5)Me(5))(2)Co](+) [PF(6)](-) whose single-crystal structure has been determined by X-ray diffraction. The (13)C, (19)F, and (31)P MAS NMR spectra of the mixed crystals show that the respective two closest paramagnetic ions in the lattice delocalize spin density to [(C(5)Me(5))(2)Co](+), [(C(5)Me(5))(2)Ni](+), and [PF(6)](-). In [(C(5)Me(5))(2)M](+), about 10(-4) au per carbon atom are transferred.
Journal of the American Chemical Society 10/2002; 124(36):10823-32. · 9.91 Impact Factor
