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Noy R, Bassal R, Ostrovsky D, Cohen J, Ishai R, Cohen-Vaizer M, Vaisbuch Y. Surgical Approaches to Petrous Apex Cholesterol Granulomas: A Systematic Review and Network Meta-analysis. Laryngoscope 2024; 134:1540-1550. [PMID: 37812326 DOI: 10.1002/lary.31073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 08/10/2023] [Accepted: 09/11/2023] [Indexed: 10/10/2023]
Abstract
OBJECTIVE To compare the outcomes of different surgical approaches to petrous apex cholesterol granulomas (PACG). DATA SOURCES PubMed, Embase, Google Scholar, Cochrane, and Web of Science. REVIEW METHODS Following the Preferred Reporting Items for Systematic Reviews and Meta-analyses-Network Meta-analyses guidelines, databases were searched from inception to November 31, 2022. Studies comparing two or more approaches were included. Reviews and population studies were excluded. The main outcome measures were the resolution of symptoms, serviceable hearing, complication, and revision rates. RESULTS The search yielded 2132 studies. After applying inclusion and exclusion criteria, 15 studies remained, consisting of 214 patients treated with lateral approaches (n = 182) or anterior endonasal approaches (n = 32). The efficacy of lateral and anterior endonasal approaches in achieving symptom resolution was comparable (73% vs. 68%, p = 0.5). Both exhibited similar rates of complications (33% vs. 37%, p = 0.3), albeit with distinct profiles. Lateral approaches were associated with higher rates of facial palsy and sensorineural hearing loss (44% vs. 18%, p = 0.03). Anterior endonasal approaches demonstrated higher rates of epistaxis and cerebrospinal fluid leak (15% vs. 1%, p = 0.001). Anterior endonasal approaches exhibited lower revision rates (OR: 0.35, 95% CI: 0.14-0.88). The placement of a stent in both approaches was associated with higher symptom resolution (OR: 5.12, 95% CI: 1.05-9.97) and lower revision rates (OR: 0.71, 95% CI: 0.33-0.92). CONCLUSIONS Anterior endonasal approaches yield lower revision rates compared to lateral approaches for PACG. Both approaches demonstrate similar effectiveness in symptom resolution and comparable rates of complications, with distinct profiles. Facial nerve and hearing status are important factors that should be addressed when selecting the approach. Stenting is beneficial. LEVEL OF EVIDENCE NA Laryngoscope, 134:1540-1550, 2024.
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Affiliation(s)
- Roee Noy
- Department of Otolaryngology-Head and Neck Surgery, Rambam Health Care Campus, Haifa, Israel
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Raghad Bassal
- Department of Otolaryngology-Head and Neck Surgery, Rambam Health Care Campus, Haifa, Israel
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Dmitry Ostrovsky
- Department of Otolaryngology-Head and Neck Surgery, Rambam Health Care Campus, Haifa, Israel
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Jacob Cohen
- Department of Otolaryngology-Head and Neck Surgery, Rambam Health Care Campus, Haifa, Israel
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Reuven Ishai
- Department of Otolaryngology-Head and Neck Surgery, Rambam Health Care Campus, Haifa, Israel
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Mauricio Cohen-Vaizer
- Department of Otolaryngology-Head and Neck Surgery, Rambam Health Care Campus, Haifa, Israel
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Yona Vaisbuch
- Department of Otolaryngology-Head and Neck Surgery, Rambam Health Care Campus, Haifa, Israel
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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Vugmeyster L, Ostrovsky D, Fu R. Carbon-detected deuterium solid-state NMR rotating frame relaxation measurements for protein methyl groups under magic angle spinning. Solid State Nucl Magn Reson 2024; 130:101922. [PMID: 38417233 PMCID: PMC11015826 DOI: 10.1016/j.ssnmr.2024.101922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 02/16/2024] [Accepted: 02/20/2024] [Indexed: 03/01/2024]
Abstract
Deuterium rotating frame solid-state NMR relaxation measurements (2H R1ρ) are important tools in quantitative studies of molecular dynamics. We demonstrate how 2H to 13C cross-polarization (CP) approaches under 10-40 kHz magic angle spinning rates can be combined with the 2H R1ρ blocks to allow for extension of deuterium rotating frame relaxation studies to methyl groups in biomolecules. This extension permits detection on the 13C nuclei and, hence, for the achievement of site-specific resolution. The measurements are demonstrated using a nine-residue low complexity peptide with the sequence GGKGMGFGL, in which a single selective -13CD3 label is placed at the methionine residue. Carbon-detected measurements are compared with the deuterium direct-detection results, which allows for fine-tuning of experimental approaches. In particular, we show how the adiabatic respiration CP scheme and the double adiabatic sweep on the 2H and 13C channels can be combined with the 2H R1ρ relaxation rates measurement. Off-resonance 2H R1ρ measurements are investigated in addition to the on-resonance condition, as they extent the range of effective spin-locking field.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver, CO, 80204, USA.
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado Denver, Denver, CO, 80204, USA
| | - Riqiang Fu
- National High Field Magnetic Laboratory, Tallahassee, FL, 32310, USA
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Vugmeyster L, Ostrovsky D, Rodgers A, Gwin K, Smirnov SL, McKnight CJ, Fu R. Persistence of Methionine Side Chain Mobility at Low Temperatures in a Nine-Residue Low Complexity Peptide, as Probed by 2 H Solid-State NMR. Chemphyschem 2024; 25:e202300565. [PMID: 38175858 PMCID: PMC10922872 DOI: 10.1002/cphc.202300565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 12/01/2023] [Indexed: 01/06/2024]
Abstract
Methionine side chains are flexible entities which play important roles in defining hydrophobic interfaces. We utilize deuterium static solid-state NMR to assess rotameric inter-conversions and other dynamic modes of the methionine in the context of a nine-residue random-coil peptide (RC9) with the low-complexity sequence GGKGMGFGL. The measurements in the temperature range of 313 to 161 K demonstrate that the rotameric interconversions in the hydrated solid powder state persist to temperatures below 200 K. Removal of solvation significantly reduces the rate of the rotameric motions. We employed 2 H NMR line shape analysis, longitudinal and rotation frame relaxation, and chemical exchange saturation transfer methods and found that the combination of multiple techniques creates a significantly more refined model in comparison with a single technique. Further, we compare the most essential features of the dynamics in RC9 to two different methionine-containing systems, characterized previously. Namely, the M35 of hydrated amyloid-β1-40 in the three-fold symmetric polymorph as well as Fluorenylmethyloxycarbonyl (FMOC)-methionine amino acid with the bulky hydrophobic group. The comparison suggests that the driving force for the enhanced methionine side chain mobility in RC9 is the thermodynamic factor stemming from distributions of rotameric populations, rather than the increase in the rate constant.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver CO USA 80204
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado Denver, Denver CO USA 80204
| | - Aryana Rodgers
- Department of Chemistry, University of Colorado Denver, Denver CO USA 80204
| | - Kirsten Gwin
- Department of Chemistry, University of Colorado Denver, Denver CO USA 80204
| | - Serge L. Smirnov
- Department of Chemistry, Western Washington University, Bellingham, WA 98225
| | - C. James McKnight
- Department of Pharmacology, Physiology and Biophysics, Boston University Chobanian and Avedisian School of Medicine, Boston, MA, 02118
| | - Riqiang Fu
- National High Magnetic Field Laboratory, Tallahassee, FL USA 32310
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Vugmeyster L, Au DF, Frazier B, Qiang W, Ostrovsky D. Rigidifying of the internal dynamics of amyloid-beta fibrils generated in the presence of synaptic plasma vesicles. Phys Chem Chem Phys 2024; 26:5466-5478. [PMID: 38277177 PMCID: PMC10956644 DOI: 10.1039/d3cp04824a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2024]
Abstract
We investigated the changes in internal flexibility of amyloid-β1-40 (Aβ) fibrils grown in the presence of rat synaptic plasma vesicles. The fibrils are produced using a modified seeded growth protocol, in which the Aβ concentration is progressively increased at the expense of the decreased lipid to protein ratio. The morphologies of each generation are carefully assessed at several fibrils' growth time points using transmission electron microscopy. The side-chain dynamics in the fibrils is investigated using deuterium solid-state NMR measurements, with techniques spanning line shapes analysis and several NMR relaxation rates measurements. The dynamics is probed in the site-specific fashion in the hydrophobic C-terminal domain and the disordered N-terminal domain. An overall strong rigidifying effect is observed in comparison with the wild-type fibrils generated in the absence of the membranes. In particular, the overall large-scale fluctuations of the N-terminal domain are significantly reduced, and the activation energies of rotameric inter-conversion in methyl-bearing side-chains of the core (L17, L34, M35, V36), as well as the ring-flipping motions of F19 are increased, indicating a restricted core environment. Membrane-induced flexibility changes in Aβ aggregates can be important for the re-alignment of protein aggregates within the membrane, which in turn would act as a disruption pathway of the bilayers' integrity.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver, CO, USA, 80204.
| | - Dan Fai Au
- Department of Chemistry, University of Colorado Denver, Denver, CO, USA, 80204.
| | - Bailey Frazier
- Department of Chemistry, University of Colorado Denver, Denver, CO, USA, 80204.
| | - Wei Qiang
- Department of Chemistry, Binghamton University, Binghamton, New York, USA, 13902
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado Denver, Denver, CO, USA, 80204
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Cruceta L, Sun Y, Kenyaga JM, Ostrovsky D, Rodgers A, Vugmeyster L, Yao L, Qiang W. Modulation of aggregation and structural polymorphisms of β-amyloid fibrils in cellular environments by pyroglutamate-3 variant cross-seeding. J Biol Chem 2023; 299:105196. [PMID: 37633335 PMCID: PMC10518720 DOI: 10.1016/j.jbc.2023.105196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 08/16/2023] [Accepted: 08/18/2023] [Indexed: 08/28/2023] Open
Abstract
Amyloidogenic deposition of β-amyloid (Aβ) peptides in human brain involves not only the wild-type Aβ (wt-Aβ) sequences, but also posttranslationally modified Aβ (PTM-Aβ) variants. Recent studies hypothesizes that the PTM-Aβ variants may trigger the deposition of wt-Aβ, which underlies the pathology of Sporadic Alzheimer's disease. Among PTM-Aβ variants, the pyroglutamate-3-Aβ (pyroE3-Aβ) has attracted much attention because of their significant abundances and broad distributions in senile plaques and dispersible and soluble oligomers. pyroE3-specific antibodies are being tested as potential anti-Aβ drugs in clinical trials. However, evidence that support the triggering effect of pyroE3-Aβ on wt-Aβ in cells remain lacking, which diminishes its pathological relevance. We show here that cross-seeding with pyroE3-Aβ40 leads to accelerated extracellular and intracellular aggregation of wt-Aβ40 in different neuronal cells. Cytotoxicity levels are elevated through the cross-seeded aggregation, comparing with the self-seeded aggregation of wt-Aβ40 or the static presence of pyroE3-Aβ40 seeds. For the extracellular deposition in mouse neuroblastoma Neuro2a (N2a) cells, the cytotoxicity elevation correlates positively with the seeding efficiency. Besides aggregation rates, cross-seeding with pyroE3-Aβ40 also modulates the molecular level structural polymorphisms of the resultant wt-Aβ40 fibrils. Using solid-state nuclear magnetic resonance (ssNMR) spectroscopy, we identified key structural differences between the parent pyroE3/ΔE3 and wt-Aβ40 fibrils within their fibrillar cores. Structural propagation from seeds to daughter fibrils is demonstrated to be more pronounced in the extracellular seeding in N2a cells by comparing the ssNMR spectra from different seeded wt-Aβ40 fibrils, but less significant in the intracellular seeding process in human neuroblastoma SH-SY5Y cells.
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Affiliation(s)
- Letticia Cruceta
- Department of Chemistry, Binghamton University, State University of New York, Vestal, New York, USA
| | - Yan Sun
- Small Scale System Integration and Packaging (S(3)IP), Binghamton University, Vestal, New York, USA
| | - June M Kenyaga
- Department of Chemistry, Binghamton University, State University of New York, Vestal, New York, USA
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado Denver, Denver Colorado, USA
| | - Aryana Rodgers
- Department of Chemistry, University of Colorado Denver, Denver Colorado, USA
| | - Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver Colorado, USA
| | - Lan Yao
- Small Scale System Integration and Packaging (S(3)IP), Binghamton University, Vestal, New York, USA
| | - Wei Qiang
- Department of Chemistry, Binghamton University, State University of New York, Vestal, New York, USA.
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Vugmeyster L, Rodgers A, Ostrovsky D, James McKnight C, Fu R. Deuteron off-resonance rotating frame relaxation for the characterization of slow motions in rotating and static solid-state proteins. J Magn Reson 2023; 352:107493. [PMID: 37271094 PMCID: PMC10330767 DOI: 10.1016/j.jmr.2023.107493] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 05/24/2023] [Accepted: 05/25/2023] [Indexed: 06/06/2023]
Abstract
We demonstrate the feasibility of deuterium solid-state NMR off-resonance rotating frame relaxation measurements for studies of slow motions in biomolecular solids. The pulse sequence, which includes adiabatic pulses for magnetization alignment, is illustrated for static and magic-angle spinning conditions away from rotary resonances. We apply the measurements for three systems with selective deuterium labels at methyl groups: a) a model compound, Fluorenylmethyloxycarbonyl methionine-D3 amino acid, for which the principles of the measurements and corresponding motional modeling based on rotameric interconversions are demonstrated; b) amyloid-β1-40 fibrils labeled at a single alanine methyl group located in the disordered N-terminal domain. This system has been extensively studied in prior work and here serves as a test of the method for complex biological systems. The essential features of the dynamics consist of large-scale rearrangements of the disordered N-terminal domain and the conformational exchange between the free and bound forms of the domain, the latter one due to transient interactions with the structured core of the fibrils. and c) a 15-residue helical peptide which belongs to the predicted α-helical domain near the N-terminus of apolipoprotein B. The peptide is solvated with triolein and incorporates a selectively labeled leucine methyl groups. The method permits model refinement, indicating rotameric interconversions with a distribution of rate constants.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver, CO 80204, USA.
| | - Aryana Rodgers
- Department of Chemistry, University of Colorado Denver, Denver, CO 80204, USA
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado Denver, Denver, CO 80204, USA
| | - C James McKnight
- Department of Pharmacology, Physiology and Biophysics, Boston University Chobanian and Avedisian School of Medicine, Boston, MA 02118, United States
| | - Riqiang Fu
- National High Field Magnetic Laboratory, Tallahassee, FL 32310, USA
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7
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Rodgers A, Sawaged M, Ostrovsky D, Vugmeyster L. Effect of Cross-Seeding of Wild-Type Amyloid-β 1-40 Peptides with Post-translationally Modified Fibrils on Internal Dynamics of the Fibrils Using Deuterium Solid-State NMR. J Phys Chem B 2023; 127:2887-2899. [PMID: 36952330 PMCID: PMC10257444 DOI: 10.1021/acs.jpcb.2c07817] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/24/2023]
Abstract
Post-translationally modified (PTM) amyloid-β (Aβ) species can play an important role in modulating Alzheimer's disease pathology. These relatively less populated modifications can cross-seed the wild-type Aβ peptides to produce fibrils that retain many structural and functional features of the original PTM variants. We focus on studies of internal flexibility in the cross-seeded Aβ1-40 fibrils originating from seeding with two PTM variants with modifications in the disordered N-terminal domain: ΔE3 truncation and S8-phosphorylation. We employ an array of 2H solid-state NMR techniques, including line shape analysis over a broad temperature range, longitudinal relaxation, and quadrupolar CPMG, to assess the dynamics of the cross-seeded fibrils. The focus is placed on selected side-chain sites in the disordered N-terminal domain (G9 and V12) and hydrophobic core methyl and aromatic groups (L17, L34, M35, V36, and F19). We find that many of the essential features of the dynamics present in the original PTM seeds persist in the cross-seeded fibrils, and several of the characteristic features are even enhanced. This is particularly true for the activation energies of the rotameric motions and large-scale rearrangements of the N-terminal domain. Thus, our results on the dynamics complement prior structural and cell toxicity studies, suggesting that many PTM Aβ species can aggressively cross-seed the wild-type peptide in a manner that propagates the PTM's signature.
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Affiliation(s)
- Aryana Rodgers
- Department of Chemistry, University of Colorado Denver, Denver CO USA 80204
| | - Matthew Sawaged
- Department of Chemistry, University of Colorado Denver, Denver CO USA 80204
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado Denver, Denver CO USA 80204
| | - Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver CO USA 80204
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Noy R, Ostrovsky D, Shkedy Y. Adult tonsillectomy-increased pain scores are correlated with risk of bleeding: a retrospective cohort study. Eur Arch Otorhinolaryngol 2023; 280:3437-3444. [PMID: 36941488 DOI: 10.1007/s00405-023-07931-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 03/14/2023] [Indexed: 03/23/2023]
Abstract
PURPOSE Tonsillectomy is among the most common surgical procedures performed worldwide, and post-tonsillectomy bleeding is a serious complication. This study aims to investigate the role of post-operative pain as a risk factor for bleeding in adults. METHODS A retrospective cohort study of adults who underwent tonsillectomy in a tertiary referral center between 2015-2021. Medical records were reviewed for demographics, diagnoses, surgical technique, treatments, pain scores (measured by visual analogue scale 0-10), readmissions, and bleeding events. The primary outcome was return to the operating room for hemostasis, and secondary outcomes were bleeding events and consumption of additional analgesic doses. RESULTS Of the 274 patients, 137 (50%) were males, the mean age was 30.3 ± 12 years (range 18-82), and 33 (12%) were smokers. Indications for tonsillectomy were recurrent throat infections in 213 (77.7%) patients and obstructive sleep apnea in 61 (22.3%). Surgical technique was cold dissection in 238 (86.9%) patients and electrocautery in 36 (13.1%). Primary post-tonsillectomy bleeding (< 24 h of surgery) occurred in 6 (2%) patients, and secondary bleeding (later than 24 h from tonsillectomy) in 43 (15.7%). A total of 19 (7%) patients necessitated surgical hemostasis. After controlling for technique and other confounders, high pain scores (VAS ≥ 5) on post-operative days 1 and 2 were associated with increased risk of bleeding that necessitated surgical hemostasis (adjusted odds ratio 6.9, 95% confidence interval 1.7-44.5). Other independent risk factors were male sex, age < 30 years, smoking, and recurrent throat infections. CONCLUSIONS Higher pain scores following tonsillectomy are correlated with bleeding episodes requiring surgical intervention in adults. Further studies may explore the role of different intensive pain regimens in minimizing the risk of bleeding.
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Affiliation(s)
- Roee Noy
- Department of Otolaryngology-Head and Neck Surgery, Rambam Health Care Campus, 8 Ha'Aliya Street, 3109601, Haifa, Israel.
- Technion, Israel Institute of Technology, Haifa, Israel.
| | - Dmitry Ostrovsky
- Department of Otolaryngology-Head and Neck Surgery, Rambam Health Care Campus, 8 Ha'Aliya Street, 3109601, Haifa, Israel
- Technion, Israel Institute of Technology, Haifa, Israel
| | - Yotam Shkedy
- Department of Otolaryngology-Head and Neck Surgery, Rambam Health Care Campus, 8 Ha'Aliya Street, 3109601, Haifa, Israel
- Technion, Israel Institute of Technology, Haifa, Israel
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Vugmeyster L, Rodgers A, Gwin K, Ostrovsky D, Smirnov SL. Nine-residue low-complexity disordered peptide as a model system, an NMR/CD study. bioRxiv 2023:2023.02.16.528870. [PMID: 36824859 PMCID: PMC9949077 DOI: 10.1101/2023.02.16.528870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Disordered proteins and protein segments can be crucial for biological function. In this work we present a detailed biophysical characterization of the low-complexity nine-residue peptide with the sequence GGKGMGFGL. Based on proton solution NMR chemical shifts, circular dichroism measurements, as well as the analysis of concentration dependence of NMR linewidth, proton longitudinal relaxation times, hydrogen-deuterium exchange measurements, and 15 N rotating frame NMR relaxation measurements, we conclude that the peptide is fully disordered and monomeric in solution. The peptide will serve as a model system for future structural and dynamics studies of biologically relevant disordered peptides in solution and solid states.
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Vugmeyster L, Nichols PJ, Ostrovsky D, McKnight CJ, Vögeli B. Slow methyl axes motions in perdeuterated villin headpiece subdomain probed by cross-correlated NMR relaxation measurements. Magnetochemistry 2023; 9:33. [PMID: 36776538 PMCID: PMC9910280 DOI: 10.3390/magnetochemistry9010033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Protein methyl groups can participate in multiple motional modes on different time scales. Sub-nanosecond to nano-second time scale motions of methyl axes are particularly challenging to detect for small proteins in solutions. In this work we employ NMR relaxation interference between the methyl H-H/H-C dipole-dipole interactions [Sun&Tugarinov, J. Magn. Reason. 2012] to characterize methyl axes motions as a function of temperature in a small model protein villin headpiece subdomain (HP36), in which all non-exchangeable protons are deuterated with the exception of methyl groups of leucine and valine residues. The data points to the existence of slow motional modes of methyl axes on sub-nanosecond to nanosecond time scales. Further, at high temperatures for which the overall tumbling of the protein is on the order of 2 ns, we observe a coupling between the slow internal motion and the overall molecular tumbling, based on the anomalous order parameters and their temperature-dependent trends. The addition of 28%(w/w) glycerol-d8 increases the viscosity of the solvent and separates the timescales of internal and overall tumbling, thus permitting for another view of the necessity of the coupling assumption for these sites at high temperatures.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado at Denver, Denver, CO 80204
| | - Parker J. Nichols
- Department of Biochemistry and Molecular Genetics, University of Colorado, School of Medicine, Anschutz Medical Campus, Aurora, CO, 80045
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado at Denver, Denver, CO 80204
| | - C. James McKnight
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA, 02118
| | - Beat Vögeli
- Department of Biochemistry and Molecular Genetics, University of Colorado, School of Medicine, Anschutz Medical Campus, Aurora, CO, 80045
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Vugmeyster L, Ostrovsky D, Greenwood A, Fu R. Deuteron rotating frame relaxation for the detection of slow motions in rotating solids. J Magn Reson 2022; 337:107171. [PMID: 35219160 PMCID: PMC8994516 DOI: 10.1016/j.jmr.2022.107171] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 02/15/2022] [Accepted: 02/16/2022] [Indexed: 06/06/2023]
Abstract
We demonstrate experimental and computational approaches for measuring 2H rotating frame NMR relaxation for solid samples under magic angle spinning (MAS) conditions. The relaxation properties of the deuterium spin-1 system are dominated by the reorientation of the anisotropic quadrupolar tensors, with the effective quadrupolar coupling constant around 55 kHz for methyl groups. The technique is demonstrated using the model compound dimethyl-sulfone at MAS rates of 10 and 60 kHz as well as for an amyloid fibril sample comprising an amyloid-β (1-40) protein with a selective methyl group labeled in the disordered domain of the fibrils, at an MAS rate of 8 kHz. For both systems, the motional parameters fall well within the ranges determined by other techniques, thus validating its feasibility. Experimental and computational factors such as i) the probe's radio frequency inhomogeneity profiles, ii) rotary resonances at conditions for which the spin-lock field strength matches the half- or full-integer of the MAS rate, iii) the choice of MAS rates and spin-lock field strengths, and iv) simulations that account for the interconversion of multiple coherences for the spin-1 system under MAS and deviations from the analytical Redfield treatment are thoroughly considered.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver, CO 80204, USA.
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado Denver, Denver, CO 80204, USA
| | - Alexander Greenwood
- Department of Chemistry, University of Cincinnati, Cincinnati, OH 45221-0172, USA
| | - Riqiang Fu
- National High Field Magnetic Laboratory, Tallahassee, FL 32310, USA
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Vugmeyster L, Au DF, Smith MC, Ostrovsky D. Comparative Hydrophobic Core Dynamics Between Wild-Type Amyloid-β Fibrils, Glutamate-3 Truncation, and Serine-8 Phosphorylation. Chemphyschem 2022; 23:e202100709. [PMID: 34837296 PMCID: PMC9484291 DOI: 10.1002/cphc.202100709] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/10/2021] [Indexed: 02/06/2023]
Abstract
Post-translational modifications (PTMs) of amyloid-β (Aβ) species are implicated in the modulation of overall toxicities and aggregation propensities. We investigated the internal dynamics in the hydrophobic core of the truncated ΔE3 mutant fibrils of Aβ1-40 and compared them with prior and new data for wild-type fibrils as well as with phosphorylated S8 fibrils. Deuteron static solid-state NMR techniques, spanning line-shape analysis, longitudinal relaxation, and chemical exchange saturation transfer methods, were employed to assess the rotameric jumps of several methyl-bearing and aromatic groups in the core of the fibrils. Taken together, the results indicate the rather significant influence of the PTMs on the hydrophobic core dynamics, which propagates far beyond the local site of the chemical modification. The phosphorylated S8 fibrils display an overall rigidifying of the core based on the higher activation barriers of motions than the wild-type fibrils, whereas the ΔE3 fibrils induce a broader variety of changes, some of which are thermodynamic in nature rather than the kinetic ones.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver CO USA 80204, corresponding author
| | - Dan Fai Au
- Department of Chemistry, University of Colorado Denver, Denver CO USA 80204
| | - Matthew C. Smith
- Department of Chemistry, University of Colorado Denver, Denver CO USA 80204
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado Denver, Denver CO USA 80204
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13
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Muir O, Weinfeld JN, Ruiz D, Ostrovsky D, Fiolhais M, MacMillan C. Mental health clinicians' attitudes toward narcissistic personality disorder. Personal Disord 2021; 12:389-399. [PMID: 34793187 DOI: 10.1037/per0000510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Narcissistic personality disorder (NPD) is an underdiagnosed psychiatric condition in which there is minimal research to support a validated treatment regimen. As a result, it is unclear how mental health practitioners approach NPD patients and the outcomes of clinical management. Given this gap in current mental health practice, this article explores the attitudes of clinicians toward treating NPD patients and the clinician-reported outcomes of managing NPD patients. The study uses a qualitative and quantitative approach to analyze the results of a 16-question survey about clinicians' experiences working with NPD patients. 173 participants were recruited from online psychology interest forums between April 2019 to August 2019. The data were analyzed using the Statistical Package for the Social Scientist (SPSS-26). The qualitative data showed that clinicians find NPD patients to be difficult and challenging. Additionally, clinicians report minimal experience treating NPD and high treatment drop-out rates. The quantitative data were evaluated using Pearson correlation coefficients. These results show that clinicians who view NPD as a diagnosis worth treating report more benefit from their care. These results also showed that participants who report formal didactic training in NPD have better results with their patients. The data also show that clinicians feel group therapy can be helpful in treating NPD, despite reporting that it is often not offered to NPD patients. This is an area that can direct future NPD research to develop a comprehensive approach to NPD management. (PsycInfo Database Record (c) 2021 APA, all rights reserved).
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14
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Vugmeyster L, Ostrovsky D. Deuterium solid-state NMR quadrupolar order rotating frame relaxation with applications to amyloid-β fibrils. Magn Reson Chem 2021; 59:853-863. [PMID: 33161607 PMCID: PMC8105426 DOI: 10.1002/mrc.5114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 10/06/2020] [Accepted: 11/03/2020] [Indexed: 05/27/2023]
Abstract
We describe a new method for measuring molecular dynamics based on the deuterium solid-state nuclear magnetic resonance (NMR) quadrupolar order rotating frame relaxation rate R1ρ,Q under static conditions. The observed quadrupolar order coherence is created using the broad-band Jeener-Broekaert excitation and is locked with a weak radio frequency (RF) field. We describe the experimental and theoretical approaches and show applications to a selectively deuterated valine side chain of the phosphorylated amyloid-β (1-40) fibrils phosphorylated at the serine-8 position. The R1ρ,Q rate is sensitive to the rotameric exchange mode. For biological samples, the low spin-lock field in the 5- to 10-kHz range has the advantage of avoiding sample heating and dehydration. Thus, it provides an alternative to approaches based on single-quantum coherence, which require larger spin-lock fields.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver CO USA 80204
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado Denver, Denver CO USA 80204
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15
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Vugmeyster L, Ostrovsky D, Greenwood A, Fu R. Deuteron Chemical Exchange Saturation Transfer for the Detection of Slow Motions in Rotating Solids. Front Mol Biosci 2021; 8:705572. [PMID: 34386521 PMCID: PMC8353179 DOI: 10.3389/fmolb.2021.705572] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 07/12/2021] [Indexed: 01/10/2023] Open
Abstract
We utilized the 2H Chemical Exchange Saturation Transfer (CEST) technique under magic angle spinning (MAS) conditions to demonstrate the feasibility of the method for studies of slow motions in the solid state. For the quadrupolar anisotropic interaction, the essence of CEST is to scan the saturation pattern over a range of offsets corresponding to the entire spectral region(s) for all conformational states involved, which translates into a range of −60–+ 60 kHz for methyl groups. Rotary resonances occur when the offsets are at half-and full-integer of the MAS rates. The choice of the optimal MAS rate is governed by the condition to reduce the number of rotary resonances in the CEST profile patterns and retain a sufficiently large quadrupolar interaction active under MAS to maintain sensitivity to motions. As examples, we applied this technique to a well-known model compound dimethyl-sulfone (DMS) as well as amyloid-β fibrils selectively deuterated at a single methyl group of A2 belonging to the disordered domain. It is demonstrated that the obtained exchange rate between the two rotameric states of DMS at elevated temperatures fell within known ranges and the fitted model parameters for the fibrils agree well with the previously obtained value using static 2H NMR techniques. Additionally, for the fibrils we have observed characteristic broadening of rotary resonances in the presence of conformational exchange, which provides implications for model selection and refinement. This work sets the stage for future potential extensions of the 2H CEST under MAS technique to multiple-labeled samples in small molecules and proteins.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver, CO, United States
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado Denver, Denver, CO, United States
| | - Alexander Greenwood
- Department of Chemistry, University of Cincinnati, Cincinnati, OH, United States
| | - Riqiang Fu
- National High Field Magnetic Laboratory, Tallahassee, FL, United States
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16
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Shinnawi S, Kopaev I, Na’ara S, Eran A, Sviri G, Ostrovsky D, Gil Z. Long-Term Quality of Life after Endoscopic Pituitary Adenoma Surgery with Nasoseptal Flap Reconstruction. Rambam Maimonides Med J 2021; 12:RMMJ.10435. [PMID: 33938800 PMCID: PMC8092951 DOI: 10.5041/rmmj.10435] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION Endoscopic endonasal transsphenoidal surgery (EETS) on the pituitary gland is considered safe and efficacious. The nasoseptal flap (NSF) is sometimes used to prevent or repair postoperative cerebrospinal fluid (CSF) leaks. Few investigators have quantified long-term quality-of-life (QOL) outcomes regarding sinonasal measures after EETS, with or without involvement of the NSF. This study assesses whether the septal flap affects sinonasal QOL outcomes for patients receiving EETS for pituitary adenoma. METHODS AND MATERIALS This is a retrospective study of patients who underwent EETS between 2013 and 2018. A total of 62 adults completed the Sinonasal Outcome Test-22 (SNOT-22) at least one year after the surgery. Outcome measures were compared between patients who underwent EETS with and without septal flap reconstruction. RESULTS For the entire cohort, there were 14 patients (22.6%) who had septal flap reconstruction and 48 patients (77.4%) who did not. Patient demographics, tumor characteristics, surgical outcomes, and duration between surgery and completion of the questionnaire were similar for both groups. The mean SNOT-22 scores in the no reconstruction (NR) group and the nasoseptal flap reconstruction (NSFR) group were similar (P=0.9). In terms of SNOT-22 subdomains (rhinologic symptoms, extranasal rhinologic symptoms, ear/facial symptoms, psychological dysfunction, and sleep dysfunction), no significant differences were found when comparing the groups. CONCLUSION As compared with no reconstructive involvement, NSF utilization does not affect the QOL and nasal symptoms of patients undergoing EETS.
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Affiliation(s)
- Shadi Shinnawi
- Department of Otolaryngology-Head and Neck Surgery, Rambam Health Care Campus, Haifa, Israel
- The Laboratory for Applied Cancer Research, Rambam Health Care Campus, Haifa, Israel
| | - Ilya Kopaev
- Department of Otolaryngology-Head and Neck Surgery, Rambam Health Care Campus, Haifa, Israel
| | - Shorook Na’ara
- Department of Otolaryngology-Head and Neck Surgery, Rambam Health Care Campus, Haifa, Israel
- The Laboratory for Applied Cancer Research, Rambam Health Care Campus, Haifa, Israel
| | - Ayelet Eran
- Department of Radiology, Rambam Health Care Campus, Haifa, Israel
| | - Gil Sviri
- Department of Neurosurgery, Rambam Health Care Campus, Haifa, Israel
| | - Dmitry Ostrovsky
- Department of Otolaryngology-Head and Neck Surgery, Rambam Health Care Campus, Haifa, Israel
| | - Ziv Gil
- Department of Otolaryngology-Head and Neck Surgery, Rambam Health Care Campus, Haifa, Israel
- The Laboratory for Applied Cancer Research, Rambam Health Care Campus, Haifa, Israel
- To whom correspondence should be addressed. E-mail:
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Vugmeyster L, Au DF, Ostrovsky D, Rickertsen DRL, Reed SM. Dynamics of Serine-8 Side-Chain in Amyloid-β Fibrils and Fluorenylmethyloxycarbonyl Serine Amino Acid, Investigated by Solid-State Deuteron NMR. J Phys Chem B 2020; 124:4723-4731. [PMID: 32396356 DOI: 10.1021/acs.jpcb.0c02490] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Serine side-chains are strategic sites of post-translational modifications, and it is important to establish benchmarks of their internal dynamics. In this work, we compare the dynamics of serine side-chains in several biologically important systems: serine-8 in the disordered domain of Aβ1-40 fibrils in the hydrated and dry states and fluorenylmethyloxycarbonyl (Fmoc) serine with the bulky group that mimics the hydrophobicity of the fibril contacts yet lacks the complexity of the protein system. Using deuterium solid-state NMR static line shape and longitudinal relaxation techniques in the 310 to 180 K temperature range, we compare the main features of the dynamics in these systems. The main motional modes in the fibrils are large-scale fluctuations in the hydrated state of the fibrils as well as local motions such as 3-site jumps of the Cβ deuterons at high temperatures and small-angle fluctuations of the Cα-Cβ axis at low temperatures. In the hydrated fibrils, two distinct states are present with vastly different extents of large-scale diffusive motions and 3-site-jump rate constants. The hydrated state at the physiological conditions is dominated by the "free" state undergoing large-scale diffusive motions and very fast local 3-site jumps, while in the "bound" state, these large-scale motions are quenched due to transient inter- and intramolecular interactions. Additionally, in the bound state, the 3-site-jump motions are orders of magnitude slower. Details of the dynamics in the serine side-chain are dependent on fine structural features and hydration levels of the systems.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver, Colorado 80204, United States
| | - Dan Fai Au
- Department of Chemistry, University of Colorado Denver, Denver, Colorado 80204, United States
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado Denver, Denver, Colorado 80204, United States
| | | | - Scott M Reed
- Department of Chemistry, University of Colorado Denver, Denver, Colorado 80204, United States
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18
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Vugmeyster L, Ostrovsky D, Fu R. Deuteron Quadrupolar Chemical Exchange Saturation Transfer (Q-CEST) Solid-State NMR for Static Powder Samples: Approach and Applications to Amyloid-β Fibrils. Chemphyschem 2020; 21:220-231. [PMID: 31805217 PMCID: PMC7002291 DOI: 10.1002/cphc.201901053] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Revised: 11/30/2019] [Indexed: 12/26/2022]
Abstract
We provide an experimental and computational framework for 2 H quadrupolar chemical exchange saturation transfer NMR experiments (Q-CEST) under static solid-state conditions for the quantification of dynamics on μs-ms timescales. Simulations using simple 2-site exchange models provide insights into the relation between spin dynamics and motions. Biological applications focus on two sites of amyloid-β fibrils in the 3-fold symmetric polymorph. The first site, the methyl group of A2 of the disordered N-terminal domain, undergoes diffusive motions and conformational exchange due to transient interactions. Earlier 2 H rotating frame relaxation and quadrupolar CPMG measurements are combined with the Q-CEST approach to characterize the multiple conformational states of the domain. The second site, the methyl group of M35, spans the water-accessible cavity inside the fibrils' core and undergoes extensive rotameric exchange. Q-CEST permits us to refine the rotameric exchange model for this site and allows the more precise determination of populations and rotameric exchange rate constants than line shape analysis.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver, CO 80204, USA
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado Denver, Denver, CO 80204, USA
| | - Riqiang Fu
- National High Field Magnetic Laboratory, Tallahassee, FL 32310, USA
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19
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Vugmeyster L, Au DF, Ostrovsky D, Kierl B, Fu R, Hu ZW, Qiang W. Effect of Post-Translational Modifications and Mutations on Amyloid-β Fibrils Dynamics at N Terminus. Biophys J 2019; 117:1524-1535. [PMID: 31570231 PMCID: PMC6817547 DOI: 10.1016/j.bpj.2019.09.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 09/01/2019] [Accepted: 09/09/2019] [Indexed: 02/04/2023] Open
Abstract
We investigate the variability in the dynamics of the disordered N-terminal domain of amyloid-β fibrils (Aβ), comprising residues 1-16 of Aβ1-40, due to post-translational modifications and mutations in the β-bend regions known to modulate aggregation properties. Using 2H static solid-state NMR approaches, we compare the dynamics in the wild-type Aβ fibrils in the threefold symmetric polymorph with the fibrils from three post-translational modification sequences: isoaspartate-D7, the phosphorylation of S8, and an N-terminal truncation ΔE3. Additional comparisons are made with the mutants in the β-bend region (residues 21-23) corresponding to the familial Osaka E22Δ deletion and D23N Iowa mutation. We also include the aggregates induced by Zn2+ ions. The dynamics are probed at the F4 and G9 positions. The main motional model involves two free states undergoing diffusion and conformational exchanges with the bound state in which the diffusion is quenched because of transient interactions involving fibril core and other intrastrand contacts. The fraction of the bound state increases in a sigmoidal fashion with a decrease in temperature. There is clear variability in the dynamics: the phosphorylation of S8 variant is the most rigid at the G9 site in line with structural studies, the ΔE3 fibrils are more flexible at the G9 site in line with the morphological fragmentation pattern, the Zn-induced aggregates are the most mobile, and the two β-bend mutants have the strongest changes at the F4 site toward higher rigidity. Overall, the changes underlie the potential role of conformational ensembles in setting the stage for aggregation-prone states.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver, Colorado.
| | - Dan F Au
- Department of Chemistry, University of Colorado Denver, Denver, Colorado
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado Denver, Denver, Colorado
| | - Brian Kierl
- Department of Chemistry, University of Colorado Denver, Denver, Colorado
| | - Riqiang Fu
- National High Field Magnetic Laboratory, Tallahassee, Florida
| | - Zhi-Wen Hu
- Department of Chemistry, Binghamton University, Binghamton, New York
| | - Wei Qiang
- Department of Chemistry, Binghamton University, Binghamton, New York
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20
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Vugmeyster L, Au DF, Ostrovsky D, Fu R. Deuteron Solid-State NMR Relaxation Measurements Reveal Two Distinct Conformational Exchange Processes in the Disordered N-Terminal Domain of Amyloid-β Fibrils. Chemphyschem 2019; 20:1680-1689. [PMID: 31087613 PMCID: PMC6663588 DOI: 10.1002/cphc.201900363] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 05/12/2019] [Indexed: 12/26/2022]
Abstract
We employed deuterium solid-state NMR techniques under static conditions to discern the details of the μs-ms timescale motions in the flexible N-terminal subdomain of Aβ1-40 amyloid fibrils, which spans residues 1-16. In particular, we utilized a rotating frame (R1ρ ) and the newly developed time domain quadrupolar Carr-Purcell-Meiboom-Gill (QCPMG) relaxation measurements at the selectively deuterated side chains of A2, H6, and G9. The two experiments are complementary in terms of probing somewhat different timescales of motions, governed by the tensor parameters and the sampling window of the magnetization decay curves. The results indicated two mobile "free" states of the N-terminal domain undergoing global diffusive motions, with isotropic diffusion coefficients of 0.7-1 ⋅ 108 and 0.3-3 ⋅ 106 ad2 s-1 . The free states are also involved in the conformational exchange with a single bound state, in which the diffusive motions are quenched, likely due to transient interactions with the structured hydrophobic core. The conformational exchange rate constants are 2-3 ⋅ 105 s-1 and 2-3 ⋅ 104 s-1 for the fast and slow diffusion free states, respectively.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver CO, USA, 80204
| | - Dan Fai Au
- Department of Chemistry, University of Colorado Denver, Denver CO, USA, 80204
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado Denver, Denver CO, USA, 80204
| | - Riqiang Fu
- National High Field Magnetic Laboratory, Tallahassee, FL, 32310
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Abstract
The structural polymorphism in β-amyloid (Aβ) plaques from Alzheimer disease (AD) has been recognized as an important pathological factor. Plaques from sporadic AD patients contain fibrillar deposits of various amyloid proteins/peptides, including posttranslational modified Aβ (PTM-Aβ) subtypes. Although many PTM-Aβs were shown to accelerate the fibrillation process, increase neuronal cytotoxicity of aggregates, or enhance the stability of fibrils, the contribution of PTM-Aβs to structural polymorphisms and their pathological roles remains unclear. We report here the NMR-based structure for the Ser-8-phosphorylated 40-residue Aβ (pS8-Aβ40) fibrils, which shows significant difference to the wild-type fibrils, with higher cross-seeding efficiency and thermodynamic stability. Given these physicochemical properties, the structures originated from pS8-Aβ40 fibrils may potentially dominate the polymorphisms in the mixture of wild-type and phosphorylated Aβ deposits. Our results imply that Aβ subtypes with "seeding-prone" properties may influence the polymorphisms of amyloid plaques through the cross-seeding process.
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Affiliation(s)
- Zhi-Wen Hu
- Department of Chemistry, Binghamton University, Binghamton, NY 13902
| | - Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver, CO 80204;
| | - Dan Fai Au
- Department of Chemistry, University of Colorado Denver, Denver, CO 80204
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado Denver, Denver, CO 80204
| | - Yan Sun
- Health Science Core Facility, Small Scale System Integration and Packaging Center, Binghamton University, Binghamton, NY 13902
| | - Wei Qiang
- Department of Chemistry, Binghamton University, Binghamton, NY 13902;
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22
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Au DF, Ostrovsky D, Fu R, Vugmeyster L. Solid-state NMR reveals a comprehensive view of the dynamics of the flexible, disordered N-terminal domain of amyloid-β fibrils. J Biol Chem 2019; 294:5840-5853. [PMID: 30737281 DOI: 10.1074/jbc.ra118.006559] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Revised: 02/08/2019] [Indexed: 11/06/2022] Open
Abstract
Amyloid fibril deposits observed in Alzheimer's disease comprise amyloid-β (Aβ) protein possessing a structured hydrophobic core and a disordered N-terminal domain (residues 1-16). The internal flexibility of the disordered domain is likely essential for Aβ aggregation. Here, we used 2H static solid-state NMR methods to probe the dynamics of selected side chains of the N-terminal domain of Aβ1-40 fibrils. Line shape and relaxation data suggested a two-state model in which the domain's free state undergoes a diffusive motion that is quenched in the bound state, likely because of transient interactions with the structured C-terminal domain. At 37 °C, we observed freezing of the dynamics progressively along the Aβ sequence, with the fraction of the bound state increasing and the rate of diffusion decreasing. We also found that without solvation, the diffusive motion is quenched. The solvent acted as a plasticizer reminiscent of its role in the onset of global dynamics in globular proteins. As the temperature was lowered, the fraction of the bound state exhibited sigmoidal behavior. The midpoint of the freezing curve coincided with the bulk solvent freezing for the N-terminal residues and increased further along the sequence. Using 2H R 1ρ measurements, we determined the conformational exchange rate constant between the free and bound states under physiological conditions. Zinc-induced aggregation leads to the enhancement of the dynamics, manifested by the faster conformational exchange, faster diffusion, and lower freezing-curve midpoints.
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Affiliation(s)
- Dan Fai Au
- From the Department of Chemistry, University of Colorado, Denver, Colorado 80204
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado, Denver, Colorado 80204
| | - Riqiang Fu
- National High Field Magnetic Laboratory, Tallahassee, Florida 32310
| | - Liliya Vugmeyster
- From the Department of Chemistry, University of Colorado, Denver, Colorado 80204.
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23
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Vugmeyster L, Griffin A, Ostrovsky D, Bhattacharya S, Nichols PJ, McKnight CJ, Vögeli B. Correlated motions of C'-N and C α-C β pairs in protonated and per-deuterated GB3. J Biomol NMR 2018; 72:39-54. [PMID: 30121872 PMCID: PMC6218248 DOI: 10.1007/s10858-018-0205-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 08/09/2018] [Indexed: 06/08/2023]
Abstract
We investigated correlated µs-ms time scale motions of neighboring 13C'-15N and 13Cα-13Cβ nuclei in both protonated and perdeuterated samples of GB3. The techniques employed, NMR relaxation due to cross-correlated chemical shift modulations, specifically target concerted changes in the isotropic chemical shifts of the two nuclei associated with spatial fluctuations. Field-dependence of the relaxation rates permits identification of the parameters defining the chemical exchange rate constant under the assumption of a two-site exchange. The time scale of motions falls into the intermediate to fast regime (with respect to the chemical shift time scale, 100-400 s-1 range) for the 13C'-15N pairs and into the slow to intermediate regime for the 13Cα-13Cβ pairs (about 150 s-1). Comparison of the results obtained for protonated and deuterated GB3 suggests that deuteration has a tendency to reduce these slow scale correlated motions, especially for the 13Cα-13Cβ pairs.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado at Denver, 1201 Larimer Street, Denver, CO, 80204, USA.
| | - Aaron Griffin
- Department of Chemistry, University of Colorado at Denver, 1201 Larimer Street, Denver, CO, 80204, USA
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado at Denver, Denver, CO, 80204, USA
| | | | - Parker J Nichols
- Department of Biochemistry and Molecular Genetics, University of Colorado, School of Medicine, Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - C James McKnight
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA, 02118, USA
| | - Beat Vögeli
- Department of Biochemistry and Molecular Genetics, University of Colorado, School of Medicine, Anschutz Medical Campus, Aurora, CO, 80045, USA
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Vugmeyster L, Ostrovsky D. Basic experiments in 2H static NMR for the characterization of protein side-chain dynamics. Methods 2018; 148:136-145. [PMID: 29705208 PMCID: PMC6133770 DOI: 10.1016/j.ymeth.2018.04.030] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 04/02/2018] [Accepted: 04/24/2018] [Indexed: 12/23/2022] Open
Abstract
The focus of this review is the basic methodology for applications of static deuteron NMR for studies of dynamics in the side chains of proteins. We review experimental approaches for the measurements of static line shapes and relaxation rates as well as signal enhancement strategies using the multiple echo acquisition scheme. Further, we describe computational strategies for modeling jump and diffusive motions underlying experimental data. Applications are chosen from studies of amyloid fibrils comprising the amyloid-β protein.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver, CO 80204, USA.
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado Denver, Denver, CO 80204, USA
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25
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Vugmeyster L, Ostrovsky D. Deuterium Rotating Frame NMR Relaxation Measurements in the Solid State under Static Conditions for Quantification of Dynamics. Chemphyschem 2018; 20:333-342. [PMID: 30079456 DOI: 10.1002/cphc.201800454] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Indexed: 11/07/2022]
Abstract
The feasibility of static deuterium rotating frame NMR relaxation measurements for characterization of slow timescale motions in powder systems is demonstrated. Using a model compound dimethyl sulfone-d6 , we show that these measurements yield conformational exchange rates and activation energy values in accordance with results obtained with other techniques. Furthermore, we demonstrate that the full Liouvillian approach as opposed to the Redfield approximation is necessary to analyze the experimental data.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado Denver, Denver CO, 80204, USA
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado Denver, Denver CO, 80204, USA
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26
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Abstract
We compared the dynamics of key methionine methyl groups in the water-accessible hydrophobic cavity of amyloid fibrils and Fluorenylmethyloxycarbonyl-Methionine (FMOC-Met), which renders general hydrophobicity to the environment without the complexity of the protein. Met35 in the hydrated cavity was recently found to undergo a dynamical cross-over from the dominance of methyl rotations at low temperatures to the dominance of diffusive motion of methyl axis at high temperatures. Current results indicate that in FMOC-Met this cross-over is suppressed, similar to what was observed for the dry fibrils, indicating that hydration of the cavity is driving the onset of the dynamical transition.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, 1201 Larimer Street, University of Colorado at Denver, Denver, CO 80204, USA
| | - Dmitry Ostrovsky
- Department of Mathematics, 1201 Larimer Street, University of Colorado at Denver, Denver, CO 80204, USA
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27
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Vugmeyster L, Ostrovsky D, Hoatson GL, Qiang W, Falconer IB. Solvent-Driven Dynamical Crossover in the Phenylalanine Side-Chain from the Hydrophobic Core of Amyloid Fibrils Detected by 2H NMR Relaxation. J Phys Chem B 2017; 121:7267-7275. [PMID: 28699757 PMCID: PMC5567839 DOI: 10.1021/acs.jpcb.7b04726] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Aromatic residues are important markers of dynamical changes in proteins' hydrophobic cores. In this work we investigated the dynamics of the F19 side-chain in the core of amyloid fibrils across a wide temperature range of 300 to 140 K. We utilized solid-state 2H NMR relaxation to demonstrate the presence of a solvent-driven dynamical crossover between different motional regimes, often also referred to as the dynamical transition. In particular, the dynamics are dominated by small-angle fluctuations at low temperatures and by π-flips of the aromatic ring at high temperatures. The crossover temperature is more than 43 degrees lower for the hydrated state of the fibrils compared to the dry state, indicating that interactions with water facilitate π-flips. Further, crossover temperatures are shown to be very sensitive to polymorphic states of the fibrils, such as the 2-fold and 3-fold symmetric morphologies of the wild-type protein as well as D23N mutant protofibrils. We speculate that these differences can be attributed, at least partially, to enhanced interactions with water in the 3-fold polymorph, which has been shown to have a water-accessible cavity. Combined with previous studies of methyl group dynamics, the results highlight the presence of multiple dynamics modes in the core of the fibrils, which was originally believed to be quite rigid.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado at Denver, Denver, CO 80204
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado at Denver, Denver, CO 80204
| | - Gina L. Hoatson
- Department of Physics, College of William and Mary, Williamsburg, Virginia, 23187
| | - Wei Qiang
- Department of Chemistry, Binghamton University, Binghamton, NY 13902
| | - Isaac B. Falconer
- Department of Chemistry, University of Colorado at Denver, Denver, CO 80204
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Vugmeyster L, Ostrovsky D. Static solid-state 2H NMR methods in studies of protein side-chain dynamics. Prog Nucl Magn Reson Spectrosc 2017; 101:1-17. [PMID: 28844219 PMCID: PMC5576518 DOI: 10.1016/j.pnmrs.2017.02.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 02/15/2017] [Accepted: 02/17/2017] [Indexed: 05/27/2023]
Abstract
In this review, we discuss the experimental static deuteron NMR techniques and computational approaches most useful for the investigation of side-chain dynamics in protein systems. Focus is placed on the interpretation of line shape and relaxation data within the framework of motional modeling. We consider both jump and diffusion models and apply them to uncover glassy behaviors, conformational exchange and dynamical transitions in proteins. Applications are chosen from globular and membrane proteins, amyloid fibrils, peptide adsorbed on surfaces and proteins specific to connective tissues.
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Vugmeyster L, Ostrovsky D, Clark MA, Falconer IB, Hoatson GL, Qiang W. Fast Motions of Key Methyl Groups in Amyloid-β Fibrils. Biophys J 2016; 111:2135-2148. [PMID: 27851938 PMCID: PMC5113154 DOI: 10.1016/j.bpj.2016.10.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 09/18/2016] [Accepted: 10/05/2016] [Indexed: 11/28/2022] Open
Abstract
Amyloid-β (Aβ) peptide is the major component of plaques found in Alzheimer's disease patients. Using solid-state 2H NMR relaxation performed on selectively deuterated methyl groups, we probed the dynamics in the threefold symmetric and twofold symmetric polymorphs of native Aβ as well as the protofibrils of the D23N mutant. Specifically, we investigated the methyl groups of two leucine residues that belong to the hydrophobic core (L17 and L34) as well as M35 residues belonging to the hydrophobic interface between the cross-β subunits, which has been previously found to be water-accessible. Relaxation measurements performed over 310-140 K and two magnetic field strengths provide insights into conformational variability within and between polymorphs. Core packing variations within a single polymorph are similar to what is observed for globular proteins for the core residues, whereas M35 exhibits a larger degree of variability. M35 site is also shown to undergo a solvent-dependent dynamical transition in which slower amplitude motions of methyl axes are activated at high temperature. The motions, modeled as a diffusion of methyl axis, have activation energy by a factor of 2.7 larger in the twofold compared with the threefold polymorph, whereas D23N protofibrils display a value similar to the threefold polymorph. This suggests enhanced flexibility of the hydrophobic interface in the threefold polymorph. This difference is only observed in the hydrated state and is absent in the dry fibrils, highlighting the role of solvent at the cavity. In contrast, the dynamic behavior of the core is hydration-independent.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado at Denver, Denver, Colorado.
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Colorado at Denver, Denver, Colorado
| | - Matthew A Clark
- Department of Chemistry, University of Alaska Anchorage, Anchorage, Alaska
| | - Isaac B Falconer
- Department of Chemistry, University of Colorado at Denver, Denver, Colorado
| | - Gina L Hoatson
- Department of Physics, College of William and Mary, Williamsburg, Virginia
| | - Wei Qiang
- Department of Chemistry, Binghamton University, Binghamton, New York
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Vugmeyster L, Clark MA, Falconer IB, Ostrovsky D, Gantz D, Qiang W, Hoatson GL. Flexibility and Solvation of Amyloid-β Hydrophobic Core. J Biol Chem 2016; 291:18484-95. [PMID: 27402826 DOI: 10.1074/jbc.m116.740530] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Indexed: 11/06/2022] Open
Abstract
Amyloid fibril deposits found in Alzheimer disease patients are composed of amyloid-β (Aβ) protein forming a number of hydrophobic interfaces that are believed to be mostly rigid. We have investigated the μs-ms time-scale dynamics of the intra-strand hydrophobic core and interfaces of the fibrils composed of Aβ1-40 protein. Using solid-state (2)H NMR line shape experiments performed on selectively deuterated methyl groups, we probed the 3-fold symmetric and 2-fold symmetric polymorphs of native Aβ as well as the protofibrils of D23N Iowa mutant, associated with an early onset of Alzheimer disease. The dynamics of the hydrophobic regions probed at Leu-17, Leu-34, Val-36, and Met-35 side chains were found to be very pronounced at all sites and in all polymorphs of Aβ, with methyl axis motions persisting down to 230-200 K for most of the sites. The dominant mode of motions is the rotameric side chain jumps, with the Met-35 displaying the most complex multi-modal behavior. There are distinct differences in the dynamics among the three protein variants, with the Val-36 site displaying the most variability. Solvation of the fibrils does not affect methyl group motions within the hydrophobic core of individual cross-β subunits but has a clear effect on the motions at the hydrophobic interface between the cross-β subunits, which is defined by Met-35 contacts. In particular, hydration activates transitions between additional rotameric states that are not sampled in the dry protein. Thus, these results support the existence of water-accessible cavity recently predicted by molecular dynamics simulations and suggested by cryo-EM studies.
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Affiliation(s)
| | | | | | | | - Donald Gantz
- Boston University School of Medicine, Boston, Massachusetts 02118
| | - Wei Qiang
- Binghamton University, Binghamton, New York 13902, and
| | - Gina L Hoatson
- College of William and Mary, Williamsburg, Virginia 23187
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Abstract
In 1980, Singer and Blom published the results of their study on use of the tracheoesophageal puncture prosthesis for restoration of voice after total laryngectomy. Since then, the placement of tracheoesophageal puncture prostheses has been an integral part of rehabilitation after laryngectomy. Complications of this procedure have been recognized and are usually minimal. Inadvertent aspiration of the prosthesis is rare. Usually, patients seek help immediately after the incident. We report a case of unnoticed aspiration of a Blom-Singer prosthesis in a patient with a laryngectomy.
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Affiliation(s)
- Dmitry Ostrovsky
- Department of Otolaryngology-Head and Neck Surgery, Rambam Medical Center and Bruce Rappaport Faculty of Medicine-Technion, Haifa, Israel
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Vugmeyster L, Ostrovsky D, Villafranca T, Sharp J, Xu W, Lipton AS, Hoatson GL, Vold RL. Dynamics of Hydrophobic Core Phenylalanine Residues Probed by Solid-State Deuteron NMR. J Phys Chem B 2015; 119:14892-904. [PMID: 26529128 PMCID: PMC4970646 DOI: 10.1021/acs.jpcb.5b09299] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We conducted a detailed investigation of the dynamics of two phenylalanine side chains in the hydrophobic core of the villin headpiece subdomain protein (HP36) in the hydrated powder state over the 298-80 K temperature range. Our main tools were static deuteron NMR measurements of longitudinal relaxation and line shapes supplemented with computational modeling. The temperature dependence of the relaxation times reveals the presence of two main mechanisms that can be attributed to the ring-flips, dominating at high temperatures, and small-angle fluctuations, dominating at low temperatures. The relaxation is nonexponential at all temperatures with the extent of nonexponentiality increasing from higher to lower temperatures. This behavior suggests a distribution of conformers with unique values of activation energies. The central values of the activation energies for the ring-flipping motions are among the smallest reported for aromatic residues in peptides and proteins and point to a very mobile hydrophobic core. The analysis of the widths of the distributions, in combination with the earlier results on the dynamics of flanking methyl groups (Vugmeyster et al. J. Phys. Chem. B 2013, 117, 6129-6137), suggests that the hydrophobic core undergoes slow concerted fluctuations. There is a pronounced effect of dehydration on the ring-flipping motions, which shifts the distribution toward more rigid conformers. The crossover temperature between the regions of dominance of the small-angle fluctuations and ring-flips shifts from 195 K in the hydrated protein to 278 K in the dry one. This result points to the role of solvent in softening the core and highlights aromatic residues as markers of the protein dynamical transitions.
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Affiliation(s)
| | | | | | - Janelle Sharp
- University of Alaska Anchorage, Anchorage, Alaska, 99508
| | - Wei Xu
- College of William and Mary, Williamsburg, Virginia, 23187
| | - Andrew S. Lipton
- Pacific Northwest National Laboratory, Richland, Washington, 99354
| | | | - Robert L. Vold
- College of William and Mary, Williamsburg, Virginia, 23187
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Vugmeyster L, Ostrovsky D, Fu R. (15)N CSA tensors and (15)N-(1)H dipolar couplings of protein hydrophobic core residues investigated by static solid-state NMR. J Magn Reson 2015; 259:225-31. [PMID: 26367322 PMCID: PMC4600402 DOI: 10.1016/j.jmr.2015.08.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 08/24/2015] [Accepted: 08/28/2015] [Indexed: 06/01/2023]
Abstract
In this work, we assess the usefulness of static (15)N NMR techniques for the determination of the (15)N chemical shift anisotropy (CSA) tensor parameters and (15)N-(1)H dipolar splittings in powder protein samples. By using five single labeled samples of the villin headpiece subdomain protein in a hydrated lyophilized powder state, we determine the backbone (15)N CSA tensors at two temperatures, 22 and -35 °C, in order to get a snapshot of the variability across the residues and as a function of temperature. All sites probed belonged to the hydrophobic core and most of them were part of α-helical regions. The values of the anisotropy (which include the effect of the dynamics) varied between 130 and 156 ppm at 22 °C, while the values of the asymmetry were in the 0.32-0.082 range. The Leu-75 and Leu-61 backbone sites exhibited high mobility based on the values of their temperature-dependent anisotropy parameters. Under the assumption that most differences stem from dynamics, we obtained the values of the motional order parameters for the (15)N backbone sites. While a simple one-dimensional line shape experiment was used for the determination of the (15)N CSA parameters, a more advanced approach based on the "magic sandwich" SAMMY pulse sequence (Nevzorov and Opella, 2003) was employed for the determination of the (15)N-(1)H dipolar patterns, which yielded estimates of the dipolar couplings. Accordingly, the motional order parameters for the dipolar interaction were obtained. It was found that the order parameters from the CSA and dipolar measurements are highly correlated, validating that the variability between the residues is governed by the differences in dynamics. The values of the parameters obtained in this work can serve as reference values for developing more advanced magic-angle spinning recoupling techniques for multiple labeled samples.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Colorado at Denver, 1201 Larimer St, Denver, CO 80204, United States.
| | - Dmitry Ostrovsky
- Department of Mathematics and Department of Physics, University of Colorado at Denver, 1201 Larimer Street, Denver, CO 80204, United States
| | - Riqiang Fu
- National High Field Magnetic Laboratory, 1800 E Paul Dirac Drive, Tallahassee, FL 32310, United States
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Vugmeyster L, Ostrovsky D. Restricted diffusion of methyl groups in proteins revealed by deuteron NMR: manifestation of intra-well dynamics. J Chem Phys 2014; 140:075101. [PMID: 24559369 DOI: 10.1063/1.4865412] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The three-site hops of methyl groups are usually used as an approximation of the mechanistic description of motions responsible for the longitudinal NMR relaxation. Distinguishing between three-site hops and a more realistic mechanism of diffusion in a potential requires extended experimental and computational analysis. In order to achieve this goal, in this work the restricted diffusion is decomposed into two independent modes, namely, the jumps between potential wells and intra-well fluctuations, assuming time scale separation between these modes. This approach allows us to explain the rise in the theoretical value of T1 minimum for the restricted diffusion mechanism compared with the three-site hops mechanism via rescaling the three-site hops correlation function by the order parameter of intra-well motions. The main result of the paper is that, in general, intra-well dynamics can be visible in NMR even in the limit of large barrier heights in contrast to the common view that this limit converges to the three-site hops mechanism. Based on a previously collected detailed set of deuteron NMR relaxation and spectral data in the villin headpiece subdomain protein over a wide temperature range of 300-31 K, we are then able to conclude that the mechanism of diffusion in the threefold potential is likely to be the main source of the dynamics in this system.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Alaska Anchorage, Anchorage, Alaska 99508, USA
| | - Dmitry Ostrovsky
- Department of Mathematics, University of Alaska Anchorage, Anchorage, Alaska 99508, USA
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Ostrovsky D. A Note on the $S_2(\delta)$ Distribution and the Riemann Xi
Function. Electron Commun Probab 2014. [DOI: 10.1214/ecp.v19-3608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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36
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Vugmeyster L, Do T, Ostrovsky D, Fu R. Effect of subdomain interactions on methyl group dynamics in the hydrophobic core of villin headpiece protein. Protein Sci 2013; 23:145-56. [PMID: 24243806 DOI: 10.1002/pro.2398] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Revised: 10/16/2013] [Accepted: 11/06/2013] [Indexed: 11/06/2022]
Abstract
Thermostable villin headpiece protein (HP67) consists of the N-terminal subdomain (residues 10-41) and the autonomously folding C-terminal subdomain (residues 42-76) which pack against each other to form a structure with a unified hydrophobic core. The X-ray structures of the isolated C-terminal subdomain (HP36) and its counterpart in HP67 are very similar for the hydrophobic core residues. However, fine rearrangements of the free energy landscape are expected to occur because of the interactions between the two subdomains. We detect and characterize these changes by comparing the µs-ms time scale dynamics of the methyl-bearing side chains in isolated HP36 and in HP67. Specifically, we probe three hydrophobic side chains at the interface of the two subdomains (L42, V50, and L75) as well as at two residues far from the interface (L61 and L69). Solid-state deuteron NMR techniques are combined with computational modeling for the detailed characterization of motional modes in terms of their kinetic and thermodynamic parameters. The effect of interdomain interactions on side chain dynamics is seen for all residues but L75. Thus, changes in dynamics because of subdomain interactions are not confined to the site of perturbation. One of the main results is a two- to threefold increase in the value of the activation energies for the rotameric mode of motions in HP67 compared with HP36. Detailed analysis of configurational entropies and heat capacities complement the kinetic view of the degree of the disorder in the folded state.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Alaska Anchorage, Anchorage, Alaska
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Vugmeyster L, Ostrovsky D, Lipton AS. Origin of abrupt rise in deuteron NMR longitudinal relaxation times of protein methyl groups below 90 K. J Phys Chem B 2013; 117:6129-37. [PMID: 23627365 DOI: 10.1021/jp4021596] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In order to examine the origin of the abrupt change in the temperature dependence of (2)H NMR longitudinal relaxation times observed previously for methyl groups of L69 in the hydrophobic core of villin headpiece protein at around 90 K (Vugmeyster et al. J. Am. Chem. Soc. 2010, 132, 4038-4039), we extended the measurements to several other methyl groups in the hydrophobic core. We show that, for all methyl groups, relaxation times experience a dramatic jump several orders of magnitude around this temperature. Theoretical modeling supports the conclusion that the origin of the apparent transition in the relaxation times is due to the existence of the distribution of conformers distinguished by their activation energy for methyl three-site hops. It is also crucial to take into account the differential contribution of individual conformers into overall signal intensity. When a particular conformer approaches the regime at which its three-site hop rate constant is on the order of the quadrupolar coupling interaction constant, the intensity of the signal due to this conformer experiences a sharp drop, thus changing the balance of the contributions of different conformers into the overall signal. As a result, the observed apparent transition in the relaxation rates can be explained without the assumption of an underlying transition in the rate constants. This work in combination with earlier results also shows that the model based on the distribution of conformers explains the relaxation behavior in the entire temperature range between 300 and 70 K.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Alaska Anchorage, 3211 Providence Drive, Anchorage, Alaska 99508, United States.
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Abstract
We investigated site-specific dynamics of key methyl groups in the hydrophobic core of chicken villin headpiece subdomain (HP36) over the temperature range between 298 and 140 K using deuteron solid-state NMR longitudinal relaxation measurements. The relaxation of the longitudinal magnetization is weakly nonexponential (glassy) at high temperatures and exhibits a stronger degree of nonexponentiality below about 175 K. In addition, the characteristic relaxation times deviate from the simple Arrhenius law. We interpret this behavior via the existence of distribution of activation energy barriers for the three-site methyl jumps, which originates from somewhat different methyl environments within the local energy landscape. The width of the distribution of the activation barriers for methyl jumps is rather significant, about 1.4 kJ/mol. Our experimental results and modeling allow for the description of the apparent change at about 175 K without invoking a specific transition temperature. For most residues in the core, the relaxation behavior at high temperatures points to the existence of conformational exchange between the substates of the landscape, and our model takes into account the kinetics of this process. The observed dynamics are the same for dry and hydrated protein. We also looked at the effect of F58L mutation inside the hydrophobic core on the dynamics of one of the residues and observed a significant increase in its conformational exchange rate constant at high temperatures.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Alaska Anchorage, Anchorage, Alaska 99508, USA.
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Vugmeyster L, Do T, Ostrovsky D, Fu R, Hagedorn B. Characterization of water dynamics in frozen soils by solid-state deuteron NMR. Solid State Nucl Magn Reson 2012; 45-46:11-15. [PMID: 22578873 DOI: 10.1016/j.ssnmr.2012.04.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2011] [Revised: 03/05/2012] [Accepted: 04/20/2012] [Indexed: 05/31/2023]
Abstract
The presence of unfrozen water in soils at sub-freezing temperatures is important for biogeochemical processes as well as for the genesis of landscapes and survival of life. While several mechanisms can lead to the existence of liquid water at sub-freezing temperatures, this work focuses on the dynamical (entropic) contribution stemming from motions of water molecules at water-soil or water-ice interfaces. We demonstrate the utility of solid-state (2)H NMR methods for characterization of water dynamics in soils on various time scales. Using a sample from McMurdo Dry Valleys, Antarctica, we show the existence of dynamics spanning a milliseconds to picoseconds time scale range. Computational modeling allows for a quantitative description of the dynamics, which involves models such as an exchange between bound and free water, and changes in effective viscosity of water in the soil matrix.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Alaska Anchorage, Anchorage, AK 99508, USA.
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Vugmeyster L, Ostrovsky D, Khadjinova A, Ellden J, Hoatson GL, Vold RL. Slow motions in the hydrophobic core of chicken villin headpiece subdomain and their contributions to configurational entropy and heat capacity from solid-state deuteron NMR measurements. Biochemistry 2011; 50:10637-46. [PMID: 22085262 PMCID: PMC3366553 DOI: 10.1021/bi201515b] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have investigated microsecond to millisecond time scale dynamics in several key hydrophobic core methyl groups of chicken villin headpiece subdomain protein (HP36) using a combination of single-site labeling, deuteron solid-state NMR line shape analysis, and computational modeling. Deuteron line shapes of hydrated powder samples are dominated by rotameric jumps and show a large variability of rate constants, activation energies, and rotameric populations. Site-specific activation energies vary from 6 to 38 kJ/mol. An additional mode of diffusion on a restricted arc is significant for some sites. In dry samples, the dynamics is quenched. Parameters of the motional models allow for calculations of configurational entropy and heat capacity, which, together with the rate constants, allow for observation of interplay between thermodynamic and kinetic picture of the landscape. Mutations at key phenylalanine residues at both distal (F47L&F51L) and proximal (F58L) locations to a relatively rigid side chain of L69 have a pronounced effect on alleviating the rigidity of this side chain at room temperature and demonstrate the sensitivity of the hydrophobic core environment to such perturbations.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry, University of Alaska, Anchorage, Alaska 99508, United States.
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42
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Bar R, Netzer A, Ostrovsky D, Daitzchman M, Golz A. Abrupt tonsillar hemorrhage from a metastatic hemangiosarcoma of the breast: case report and literature review. Ear Nose Throat J 2011; 90:116-20. [PMID: 21412741 DOI: 10.1177/014556131109000309] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
We describe a case of primary breast hemangiosarcoma with tonsillar metastasis that manifested as a profuse oropharyngeal hemorrhage. The patient was a 54-year-old woman who presented to the emergency department with oral bleeding. A thorough examination revealed a distorted morphology of the left tonsil and a hemorrhage originating from it. Conservative methods to control the hemorrhage failed, and tonsillectomy was carried out. Histopathologic analysis revealed that the left tonsil contained hemangiosarcoma cells of the same kind that had been removed from the breast. Primary hemangiosarcomas of the breast are rare; when they do occur, they usually recur locally and spread hematogenously. To the best of our knowledge, this is the first case of a primary breast hemangiosarcoma with tonsillar metastasis to be reported in the literature. We present a detailed analysis of this case, and we review the relevant literature on metastatic tonsillar tumors, with attention to the role of therapeutic embolization.
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Affiliation(s)
- Ronen Bar
- Department of Otolaryngology-Head and Neck Surgery, Rambam Health Care Campus, PO Box 9602, Haifa 31096, Israel.
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Vugmeyster L, Ostrovsky D. Temperature dependence of fast carbonyl backbone dynamics in chicken villin headpiece subdomain. J Biomol NMR 2011; 50:119-27. [PMID: 21416162 PMCID: PMC3366550 DOI: 10.1007/s10858-011-9500-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Accepted: 03/02/2011] [Indexed: 05/03/2023]
Abstract
Temperature-dependence of protein dynamics can provide information on details of the free energy landscape by probing the characteristics of the potential responsible for the fluctuations. We have investigated the temperature-dependence of picosecond to nanosecond backbone dynamics at carbonyl carbon sites in chicken villin headpiece subdomain protein using a combination of three NMR relaxation rates: (13)C' longitudinal rate, and two cross-correlated rates involving dipolar and chemical shift anisotropy (CSA) relaxation mechanisms, (13)C'/(13)C'-(13)C(α) CSA/dipolar and (13)C'/(13)C'-(15)N CSA/dipolar. Order parameters have been extracted using the Lipari-Szabo model-free approach assuming a separation of the time scales of internal and molecular motions in the 2-16°C temperature range. There is a gradual deviation from this assumption from lower to higher temperatures, such that above 16°C the separation of the time scales is inconsistent with the experimental data and, thus, the Lipari-Szabo formalism can not be applied. While there are variations among the residues, on the average the order parameters indicate a markedly steeper temperature dependence at backbone carbonyl carbons compared to that probed at amide nitrogens in an earlier study. This strongly advocates for probing sites other than amide nitrogen for accurate characterization of the potential and other thermodynamics characteristics of protein backbone.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry and Environment and Natural Resources Institute, University of Alaska at Anchorage, Providence Drive, Anchorage, AK 99508, USA.
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Vugmeyster L, Ostrovsky D, Moses M, Ford JJ, Lipton AS, Hoatson GL, Vold RL. Comparative dynamics of leucine methyl groups in FMOC-leucine and in a protein hydrophobic core probed by solid-state deuteron nuclear magnetic resonance over 7-324 K temperature range. J Phys Chem B 2010; 114:15799-807. [PMID: 21077644 DOI: 10.1021/jp1082467] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Quantitative dynamics of methyl groups in 9-fluorenylmethyloxycarbonyl-leucine (FMOC-leu) have been analyzed and compared with earlier studies of methyl dynamics in chicken villin headpiece subdomain protein (HP36) labeled at L69, a key hydrophobic core position. A combination of deuteron solid-state nuclear magnetic resonance experiments over the temperature range of 7-324 K and computational modeling indicated that while the two compounds show the same modes of motions, there are marked differences in the best-fit parameters of these motions. One of the main results is that the crossover observed in the dynamics of the methyl groups in the HP36 sample at 170 K is absent in FMOC-leu. A second crossover at around 95-88 K is present in both samples. The differences in the behavior of the two compounds suggest that some of the features of methyl dynamics reflect the complexity of the protein hydrophobic core and are not determined solely by local interactions.
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Vugmeyster L, Ostrovsky D, Ford JJ, Lipton AS. Freezing of dynamics of a methyl group in a protein hydrophobic core at cryogenic temperatures by deuteron NMR spectroscopy. J Am Chem Soc 2010; 132:4038-9. [PMID: 20201523 DOI: 10.1021/ja909599k] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Methyl groups are thought to dominate the dynamics of proteins after slow collective modes of motion freeze out in a glass-transition process. In this work we investigate methyl group dynamics of a key hydrophobic core leucine residue in chicken villin headpiece subdomain protein at 140-4 K using deuteron NMR longitudinal relaxation measurements. A distinct increase in the apparent activation energy is observed at approximately 95 K, indicating an abrupt freezing of methyl group dynamics. Relaxation times at temperatures below 60 K are dominated by the deuteron tunneling mechanism.
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Vugmeyster L, Ostrovsky D, Li Y. Comparison of fast backbone dynamics at amide nitrogen and carbonyl sites in dematin headpiece C-terminal domain and its S74E mutant. J Biomol NMR 2010; 47:155-162. [PMID: 20396930 DOI: 10.1007/s10858-010-9417-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Accepted: 03/29/2010] [Indexed: 05/29/2023]
Abstract
We perform a detailed comparison of fast backbone dynamics probed at amide nitrogen versus carbonyl carbon sites for dematin headpiece C-terminal domain (DHP) and its S74E mutant (DHPS74E). Carbonyl dynamics is probed via auto-correlated longitudinal rates and transverse C'/C'-C(alpha) CSA/dipolar and C'/C'-N CSA/dipolar cross-correlated rates, while (15)N data are taken from a previous study. Resulting values of effective order parameters and internal correlation times support the conclusion that C' relaxation reports on a different subset of fast motions compared to those probed at N-H bond vectors in the same peptide planes. (13)C' order parameters are on the average 0.08 lower than (15)N order parameters with the exception of the flexible loop region in DHP. The reduction of mobility in the loop region upon the S74E mutation can be seen from the (15)N order parameters but not from the (13)C order parameters. Internal correlation times at (13)C' sites are on the average an order of magnitude longer than those at (15)N sites for the well-structured C-terminal subdomains, while the more flexible N-terminal subdomains have more comparable average internal correlation times.
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Affiliation(s)
- Liliya Vugmeyster
- Department of Chemistry and Environment and Natural Resources Institute, University of Alaska at Anchorage, 3211 Providence Drive, Anchorage, AK 99508, USA.
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Vugmeyster L, Ostrovsky D, Ford JJ, Burton SD, Lipton AS, Hoatson GL, Vold RL. Probing the dynamics of a protein hydrophobic core by deuteron solid-state nuclear magnetic resonance spectroscopy. J Am Chem Soc 2009; 131:13651-8. [PMID: 19772361 DOI: 10.1021/ja902977u] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
With the goal of investigating dynamical features of hydrophobic cores of proteins over a wide range of temperatures, the chicken villin headpiece subdomain protein (HP36) was labeled at a "single" site corresponding to any one of the two C(delta)D(3) groups of leucine-69, which is located in a key position of the core. The main techniques employed are deuteron NMR quadrupolar echo line shape analysis, and T(1Z) (Zeeman) and T(1Q) (quadrupolar order) relaxation experiments performed at 11.7 and 17.6 T over the temperature range of 112 to 298 K. The experimental data are compared with computer simulations. The deuteron line shapes give an excellent fit to a three-mode motional model that consists of (a) fast three-site rotational jumps about the pseudo C(3) methyl spinning axis, (b) slower reorientation of the spinning axis, described by diffusion along a restricted arc, and (c) large angle jumps between traces of rotameric conformers. Relaxation behavior is described by a phenomenological distribution of activation energies for three-site hops at high temperatures that collapses to a single, distinctly smaller value for lower temperatures.
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Vold RL, Hoatson GL, Vugmeyster L, Ostrovsky D, De Castro PJ. Solid state deuteron relaxation time anisotropy measured with multiple echo acquisition. Phys Chem Chem Phys 2009; 11:7008-12. [PMID: 19652835 DOI: 10.1039/b907343d] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The signal to noise ratio of solid state deuteron NMR line shapes can be significantly improved by recording multiple echoes, generated either by a quadrupole Carr-Purcell-Meiboom-Gill pulse train (QCPMG) or by magic angle spinning (MAS). It is shown in this article, theoretically and experimentally, that when these techniques are used to record partially relaxed spectra, the relaxation times of Zeeman order, T(1Z), and quadrupole order, T(1Q), measured for individual side bands in QCPMG experiments preserve relaxation time anisotropy, while rotational side bands in MAS spectra do not. The relaxation times of individual QCPMG sidebands are not identical to those measured at the same frequencies on partially relaxed quadrupole echo powder patterns, and must be computed by explicit simulation.
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Affiliation(s)
- Robert L Vold
- Department of Applied Science, College of William and Mary, Williamsburg, VA 23187-8795, USA.
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