Publications (43)183.22 Total impact
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Article: Structural insights into a wildtype domain of the oncoprotein e6 and its interaction with a PDZ domain.
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ABSTRACT: The high-risk human papilloma virus (HPV) oncoproteins E6 and E7 interact with key cellular regulators and are etiological agents for tumorigenesis and tumor maintenance in cervical cancer and other malignant conditions. E6 induces degradation of the tumor suppressor p53, activates telomerase and deregulates cell polarity. Analysis of E6 derived from a number of high risk HPV finally yielded the first structure of a wild-type HPV E6 domain (PDB 2M3L) representing the second zinc-binding domain of HPV 51 E6 (termed 51Z2) determined by NMR spectroscopy. The 51Z2 structure provides clues about HPV-type specific structural differences between E6 proteins. The observed temperature sensitivity of the well-folded wild-type E6 domain implies a significant malleability of the oncoprotein in vivo. Hence, the structural differences between individual E6 and their malleability appear, together with HPV type-specific surface exposed side-chains, to provide the structural basis for the different interaction networks reported for individual E6 proteins. Furthermore, the interaction of 51Z2 with a PDZ domain of hDlg was analyzed. Human Dlg constitutes a prototypic representative of the large family of PDZ proteins regulating cell polarity, which are common targets of high-risk HPV E6. Nine C-terminal residues of 51Z2 interact with the second PDZ domain of hDlg2. Surface plasmon resonance in conjunction with the NMR spectroscopy derived complex structure (PDB 2M3M) indicate that E6 residues N-terminal to the canonical PDZ-BM of E6 significantly contribute to this interaction and increase affinity. The structure of the complex reveals how residues outside of the classical PDZ-BM enhance the affinity of E6 towards PDZ domains. Such mechanism facilitates successful competition of E6 with cellular PDZ-binding proteins and may apply to PDZ-binding proteins of other viruses as well.PLoS ONE 01/2013; 8(4):e62584. · 4.09 Impact Factor -
Article: Solid state NMR of proteins at high MAS frequencies: symmetry-based mixing and simultaneous acquisition of chemical shift correlation spectra.
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ABSTRACT: We have carried out chemical shift correlation experiments with symmetry-based mixing sequences at high MAS frequencies and examined different strategies to simultaneously acquire 3D correlation spectra that are commonly required in the structural studies of proteins. The potential of numerically optimised symmetry-based mixing sequences and the simultaneous recording of chemical shift correlation spectra such as: 3D NCAC and 3D NHH with dual receivers, 3D NC'C and 3D C'NCA with sequential (13)C acquisitions, 3D NHH and 3D NC'H with sequential (1)H acquisitions and 3D CANH and 3D C'NH with broadband (13)C-(15)N mixing are demonstrated using microcrystalline samples of the β1 immunoglobulin binding domain of protein G (GB1) and the chicken α-spectrin SH3 domain.Journal of Biomolecular NMR 11/2012; · 3.61 Impact Factor -
Article: NMR assignment of a PDZ domain in complex with a HPV51 E6 derived N-terminally pyroglutamic acid modified peptide.
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ABSTRACT: The resonance assignment of an amino-terminal pyroglutamic acid containing peptide derived from the E6 protein of human papillomavirus (HPV) type 51 in complex with PDZ domain 2 of hDlg/SAP-97 is reported. The assignments include (1)H, (13)C and (15)N resonances for the protein and peptide in the complex and all of the peptide's pyroglutamic acid nuclei.Biomolecular NMR Assignments 03/2012; · 0.72 Impact Factor -
Article: Structural basis of β-amyloid-dependent synaptic dysfunctions.
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ABSTRACT: Learn about Alzheimer: The molecular conformation of a toxic β-amyloid oligomer structure was determined by NMR spectroscopy. The measurements show a N-terminal β strand that controls the partitioning between oligomer and protofibril formation. Targeting the N-terminus of the peptide neutralizes Aβ-dependent neuronal dysfunctions. The data have important implications for understanding the structural basis of Alzheimer's disease.Angewandte Chemie International Edition 02/2012; 51(7):1576-9. · 13.45 Impact Factor -
Article: Chemical shift correlation at high MAS frequencies employing low-power symmetry-based mixing schemes.
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ABSTRACT: An approach for conveniently implementing low-power CN ( n ) (ν) and RN ( n ) (ν) symmetry-based band-selective mixing sequences for generating homo- and heteronuclear chemical shift correlation NMR spectra of low γ nuclei in biological solids is demonstrated. Efficient magnetisation transfer characteristics are achieved by selecting appropriate symmetries requiring the application of basic RF elements of relatively long duration and numerically tailoring the RF field modulation profile of the basic element. The efficacy of the approach is experimentally shown by the acquisition of (15)N-(13)C dipolar and (13)C-(13)C scalar and dipolar coupling mediated chemical shift correlation spectra at representative MAS frequencies.Journal of Biomolecular NMR 06/2011; 50(3):277-84. · 3.61 Impact Factor -
Article: Structure-function relationship in an archaebacterial methionine sulphoxide reductase B.
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ABSTRACT: Oxidation of methionine to methionine sulphoxide (MetSO) may lead to loss of molecular integrity and function. This oxidation can be 'repaired' by methionine sulphoxide reductases (MSRs), which reduce MetSO back to methionine. Two structurally unrelated classes of MSRs, MSRA and MSRB, show stereoselectivity towards the S and the R enantiomer of the sulphoxide respectively. Interestingly, these enzymes were even maintained throughout evolution in anaerobic organisms. Here, the activity and the nuclear magnetic resonance (NMR) structure of MTH711, a zinc containing MSRB from the thermophilic, methanogenic archaebacterium Methanothermobacter thermoautotrophicus, are described. The structure appears more rigid as compared with similar MSRBs from aerobic and mesophilic organisms. No significant structural differences between the oxidized and the reduced MTH711 state can be deduced from our NMR data. A stable sulphenic acid is formed at the catalytic Cys residue upon oxidation of the enzyme with MetSO. The two non-zinc-binding cysteines outside the catalytic centre are not necessary for activity of MTH711 and are not situated close enough to the active-site cysteine to serve in regenerating the active centre via the formation of an intramolecular disulphide bond. These findings imply a reaction cycle that differs from that observed for other MSRBs.Molecular Microbiology 01/2011; 79(2):342-58. · 5.01 Impact Factor -
Article: 1H, 13C and 15N resonance assignment of a zinc-binding methionine sulfoxide reductase type-B from the thermophilic archeabacterium Methanothermobacter thermoautotrophicus.
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ABSTRACT: The (1)H, (13)C and (15)N resonance assignment of a type-B zinc-binding methionine sulfoxide reductase lacking a 'recycling' cysteine from the thermophilic archeabacterium Methanothermobacter thermoautotrophicus is reported.Biomolecular NMR Assignments 03/2010; 4(1):93-5. · 0.72 Impact Factor -
Article: Broadband 15N-13C dipolar recoupling via symmetry-based RF pulse schemes at high MAS frequencies.
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ABSTRACT: An approach for generating efficient NR(vS, vk)(n) symmetry-based dual channel RF pulse schemes for gamma-encoded broadband (15)N-(13)C dipolar recoupling at high magic angle spinning frequencies is presented. The method involves the numerical optimisation of the RF phase-modulation profile of the basic "R" element so as to obtain heteronuclear double quantum dipolar recoupling sequences with satisfactory magnetisation transfer characteristics. The basic "R" element was implemented as a sandwich of a small number of short pulses of equal duration with each pulse characterised by a RF phase and amplitude values. The performance characteristics of the sequences were evaluated via numerical simulations and (15)N-(13)C chemical shift correlation experiments. Employing such (13)C-(15)N double-quantum recoupling sequences and the multiple receiver capabilities available in the current generation of NMR spectrometers, the possibility to simultaneously acquire 3D NCC and CNH chemical shift correlation spectra is also demonstrated.Journal of Biomolecular NMR 03/2010; 47(1):7-17. · 3.61 Impact Factor -
Article: Recoupling and decoupling of nuclear spin interactions at high MAS frequencies: numerical design of CN(n)(nu) symmetry-based RF pulse schemes.
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ABSTRACT: The CN(n)(nu) class of RF pulse schemes, commonly employed for recoupling and decoupling of nuclear spin interactions in magic angle spinning solid state NMR studies of biological systems, involves the application of a basic "C" element corresponding to an RF cycle with unity propagator. In this study, the design of CN(n)(nu) symmetry-based RF pulse sequences for achieving 13C-13C double-quantum dipolar recoupling and through bond scalar coupling mediated 13C-13C chemical shift correlation has been examined at high MAS frequencies employing broadband, constant-amplitude, phase-modulated basic "C" elements. The basic elements were implemented as a sandwich of a small number of short pulses of equal duration with each pulse characterised by an RF phase value. The phase-modulation profile of the "C" element was optimised numerically so as to generate efficient RF pulse sequences. The performances of the sequences were evaluated via numerical simulations and experimental measurements and are presented here.Journal of Biomolecular NMR 07/2009; 44(4):175-84. · 3.61 Impact Factor -
Article: Numerical design of RN(n)(nu) symmetry-based RF pulse schemes for recoupling and decoupling of nuclear spin interactions at high MAS frequencies.
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ABSTRACT: An approach for the efficient implementation of RN(n)(nu) symmetry-based pulse schemes that are often employed for recoupling and decoupling of nuclear spin interactions in biological solid state NMR investigations is demonstrated at high magic-angle spinning frequencies. RF pulse sequences belonging to the RN(n)(nu) symmetry involve the repeated application of the pulse sandwich {R(phi)R(-phi)}, corresponding to a propagator U(RF) = exp(-i4phiI(z)), where phi = pinu/N and R is typically a pulse that rotates the nuclear spins through 180 degrees about the x-axis. In this study, broadband, phase-modulated 180 degrees pulses of constant amplitude were employed as the initial 'R' element and the phase-modulation profile of this 'R' element was numerically optimised for generating RN(n)(nu) symmetry-based pulse schemes with satisfactory magnetisation transfer characteristics. At representative MAS frequencies, RF pulse sequences were implemented for achieving 13C-13C double-quantum dipolar recoupling and through bond scalar coupling mediated chemical shift correlation and evaluated via numerical simulations and experimental measurements. The results from these investigations are presented here.Journal of Biomolecular NMR 07/2009; 44(4):235-44. · 3.61 Impact Factor -
Article: Design of high-power, broadband 180 degrees pulses and mixing sequences for fast MAS solid state chemical shift correlation NMR spectroscopy.
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ABSTRACT: An approach for the design of high-power, broadband 180 degrees pulses and mixing sequences for generating dipolar and scalar coupling mediated (13)C-(13)C chemical shift correlation spectra of isotopically labelled biological systems at fast magic-angle spinning frequencies without (1)H decoupling during mixing is presented. Considering RF field strengths in the range of 100-120 kHz, as typically available in MAS probes employed at high spinning speeds, and limited B (1) field inhomogeneities, the Fourier coefficients defining the phase modulation profile of the RF pulses were optimised numerically to obtain broadband inversion and refocussing pulses and mixing sequences. Experimental measurements were carried out to assess the performance characteristics of the mixing sequences reported here.Journal of Biomolecular NMR 12/2008; 43(1):51-61. · 3.61 Impact Factor -
Article: Conformational signatures of 13C chemical shifts in RNA ribose.
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ABSTRACT: The conformational dependence of (13)C chemical shift values of RNA riboses determined by liquid-state NMR spectroscopy was evaluated using data deposited for RNA structures in the RCSD and BMRB data bases. Results derived support the applicability of the canonical coordinates approach of Rossi and Harbison (J Magn Reson 151:1-8, 2001) in liquid-state NMR to assess the sugar pucker of ribose units in RNA.Journal of Biomolecular NMR 10/2008; 42(2):139-42. · 3.61 Impact Factor -
Article: MAS solid state NMR of RNAs with multiple receivers.
Journal of Biomolecular NMR 08/2008; 41(3):121-5. · 3.61 Impact Factor -
Article: Heteronuclear J cross-polarisation in liquids using amplitude and phase modulated mixing sequences.
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ABSTRACT: The design of mixing sequences for heteronuclear J cross-polarisation in the liquid state has been examined employing supercycles of amplitude/phase modulated RF pulses. The Fourier coefficients defining the modulation profiles of the pulses were optimised numerically so as to achieve efficient magnetisation transfer within the desired range of resonance offsets. A variety of supercycles, pulsewidths and RF field strengths were considered in implementing heteronuclear anisotropic and isotropic mixing sequences. The coherence transfer characteristics of the sequences obtained were evaluated by numerical simulations. The experimental performances of the sequences were tested by measurements carried out on a moderate sized protein at 750 MHz. The results presented demonstrate that the approach adopted in this study can be employed effectively to tailor, as per the experimental requirements and constraints, the RF-field modulation profiles of the pulses constituting the mixing scheme for generating heteronuclear J cross-polarisation sequences.Journal of Biomolecular NMR 05/2008; 40(4):277-83. · 3.61 Impact Factor -
Article: Broadband homonuclear TOCSY with amplitude and phase-modulated RF mixing schemes.
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ABSTRACT: We have explored the design of broadband scalar coupling mediated (13)C-(13)C and cross-relaxation suppressed (1)H-(1)H TOCSY sequences employing phase/amplitude modulated inversion pulses. Considering a variety of supercycles, pulsewidths and a RF field strength of 10 kHz, the Fourier coefficients defining the amplitude and phase modulation profiles of the 180 degrees pulses were optimised numerically so as to obtain efficient magnetisation transfer within the desired range of resonance offsets. The coherence transfer characteristics of the mixing schemes were assessed via numerical simulations and experimental measurements and were compared with commonly used sequences based on rectangular RF pulses. The efficacies of the clean (1)H-(1)H TOCSY sequences were also examined via numerical simulations for application to weakly oriented systems and sequences with efficient, broadband and clean dipolar transfer characteristics were identified. In general, the amplitude and phase modulated TOCSY sequences presented here have moderately better performance characteristics than the sequences currently employed in biomolecular NMR spectroscopy.Journal of Biomolecular NMR 05/2008; 40(4):227-37. · 3.61 Impact Factor -
Article: Solution structure of stem-loop alpha of the hepatitis B virus post-transcriptional regulatory element.
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ABSTRACT: Chronic hepatitis B virus (HBV) infections may lead to severe diseases like liver cirrhosis or hepatocellular carcinoma (HCC). The HBV post-transcriptional regulatory element (HPRE) facilitates the nuclear export of unspliced viral mRNAs, contains a splicing regulatory element and resides in the 3'-region of all viral transcripts. The HPRE consists of three sub-elements alpha (nucleotides 1151-1346), beta1 (nucleotides 1347-1457) and beta2 (nucleotides 1458-1582), which confer together full export competence. Here, we present the NMR solution structure (pdb 2JYM) of the stem-loop alpha (SLalpha, nucleotides 1292-1321) located in the sub-element alpha. The SLalpha contains a CAGGC pentaloop highly conserved in hepatoviruses, which essentially adopts a CUNG-like tetraloop conformation. Furthermore, the SLalpha harbours a single bulged G residue flanked by A-helical regions. The structure is highly suggestive of serving two functions in the context of export of unspliced viral RNA: binding sterile alpha motif (SAM-) domain containing proteins and/or preventing the utilization of a 3'-splice site contained within SLalpha.Nucleic Acids Research 04/2008; 36(5):1681-9. · 8.03 Impact Factor -
Article: 13C-13C chemical shift correlation in rotating solids without 1H decoupling during mixing.
ChemPhysChem 09/2007; 8(12):1770-3. · 3.41 Impact Factor -
Article: Broadband homonuclear chemical shift correlation at high MAS frequencies: a study of tanh/tan adiabatic RF pulse schemes without 1H decoupling during mixing.
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ABSTRACT: At high magic angle spinning (MAS) frequencies the potential of tanh/tan adiabatic RF pulse schemes for 13C chemical shift correlation without 1H decoupling during mixing has been evaluated. It is shown via numerical simulations that a continuous train of adiabatic 13C inversion pulses applied at high RF field strengths leads to efficient broadband heteronuclear decoupling. It is demonstrated that this can be exploited effectively for generating through-bond and through-space, including double-quantum, correlation spectra of biological systems at high magnetic fields and spinning speeds with no 1H decoupling applied during the mixing period. Experiments carried out on a polycrystalline sample of histidine clearly suggest that an improved signal to noise ratio can be realised by eliminating 1H decoupling during mixing.Journal of Biomolecular NMR 05/2007; 37(4):277-86. · 3.61 Impact Factor -
Article: Tailoring broadband inversion pulses for MAS solid state NMR.
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ABSTRACT: A simple approach is demonstrated for designing optimised broadband inversion pulses for MAS solid state NMR studies of biological systems. The method involves a two step numerical optimisation procedure and takes into account experimental requirements such as the pulse length, resonance offset range and extent of H(1) inhomogeneity compensation needed. A simulated annealing protocol is used initially to find appropriate values for the parameters that define the well known tanh/tan adiabatic pulse such that a satisfactory spin inversion is achieved with minimum RF field strength. This information is then used in the subsequent stage of refinement where the RF pulse characteristics are further tailored via a local optimisation procedure without imposing any restrictions on the amplitude and frequency modulation profiles. We demonstrate that this approach constitutes a generally applicable tool for obtaining pulses with good inversion characteristics. At moderate MAS frequencies the efficacy of the method is experimentally demonstrated for generating double-quantum NMR spectra via the zero-quantum dipolar recoupling scheme RFDR.Journal of Biomolecular NMR 09/2006; 35(4):275-83. · 3.61 Impact Factor -
Article: Solid state NMR at high magic angle spinning frequencies: dipolar chemical shift correlation with adiabatic inversion pulse based RF pulse schemes.
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ABSTRACT: The efficacy of hetero- and homonuclear dipolar recoupling employing tanh/tan adiabatic inversion pulse based RF pulse schemes has been examined at high magic angle spinning (MAS) frequencies via numerical simulations and experimental measurements. An approach for minimising the recoupling RF power level is presented, taking into consideration the spinning speed, the range of resonance offsets and H(1) inhomogeneities and the available RF field strength. This involves the tailoring of the frequency and amplitude modulation profiles of the inversion pulses. The applicability of tanh/tan pulse based dipolar recoupling schemes to spinning speed regimes where the performance with conventional rectangular pulses may not be satisfactory is demonstrated.Journal of Biomolecular NMR 09/2006; 35(4):241-8. · 3.61 Impact Factor
Top co-authors
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Institutions
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2006–2012
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Leibniz Institute for Age Research - Fritz Lipmann Institute
Jena, Thuringia, Germany
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2011
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Ubon Ratchathani University
Ubon Ratchathani, Changwat Ubon Ratchathani, Thailand
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