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Köhler R, Murray SM. Plasmid partitioning driven by collective migration of ParA between nucleoid lobes. Proc Natl Acad Sci U S A 2024; 121:e2319205121. [PMID: 38652748 PMCID: PMC11067062 DOI: 10.1073/pnas.2319205121] [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: 11/08/2023] [Accepted: 03/27/2024] [Indexed: 04/25/2024] Open
Abstract
The ParABS system is crucial for the faithful segregation and inheritance of many bacterial chromosomes and low-copy-number plasmids. However, despite extensive research, the spatiotemporal dynamics of the ATPase ParA and its connection to the dynamics and positioning of the ParB-coated cargo have remained unclear. In this study, we utilize high-throughput imaging, quantitative data analysis, and computational modeling to explore the in vivo dynamics of ParA and its interaction with ParB-coated plasmids and the nucleoid. As previously observed, we find that F-plasmid ParA undergoes collective migrations ("flips") between cell halves multiple times per cell cycle. We reveal that a constricting nucleoid is required for these migrations and that they are triggered by a plasmid crossing into the cell half with greater ParA. Using simulations, we show that these dynamics can be explained by the combination of nucleoid constriction and cooperative ParA binding to the DNA, in line with the behavior of other ParA proteins. We further show that these ParA flips act to equally partition plasmids between the two lobes of the constricted nucleoid and are therefore important for plasmid stability, especially in fast growth conditions for which the nucleoid constricts early in the cell cycle. Overall, our work identifies a second mode of action of the ParABS system and deepens our understanding of how this important segregation system functions.
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Affiliation(s)
- Robin Köhler
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology and Centre for Synthetic Microbiology (SYNMIKRO), Marburg35043, Germany
| | - Seán M. Murray
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology and Centre for Synthetic Microbiology (SYNMIKRO), Marburg35043, Germany
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Lamprecht O, Ratnikava M, Jacek P, Kaganovitch E, Buettner N, Fritz K, Biazruchka I, Köhler R, Pietsch J, Sourjik V. Regulation by cyclic di-GMP attenuates dynamics and enhances robustness of bimodal curli gene activation in Escherichia coli. PLoS Genet 2023; 19:e1010750. [PMID: 37186613 DOI: 10.1371/journal.pgen.1010750] [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] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 05/25/2023] [Accepted: 04/18/2023] [Indexed: 05/17/2023] Open
Abstract
Curli amyloid fibers are a major constituent of the extracellular biofilm matrix formed by bacteria of the Enterobacteriaceae family. Within Escherichia coli biofilms, curli gene expression is limited to a subpopulation of bacteria, leading to heterogeneity of extracellular matrix synthesis. Here we show that bimodal activation of curli gene expression also occurs in well-mixed planktonic cultures of E. coli, resulting in all-or-none stochastic differentiation into distinct subpopulations of curli-positive and curli-negative cells at the entry into the stationary phase of growth. Stochastic curli activation in individual E. coli cells could further be observed during continuous growth in a conditioned medium in a microfluidic device, which further revealed that the curli-positive state is only metastable. In agreement with previous reports, regulation of curli gene expression by the second messenger c-di-GMP via two pairs of diguanylate cyclase and phosphodiesterase enzymes, DgcE/PdeH and DgcM/PdeR, modulates the fraction of curli-positive cells. Unexpectedly, removal of this regulatory network does not abolish the bimodality of curli gene expression, although it affects dynamics of activation and increases heterogeneity of expression levels among individual cells. Moreover, the fraction of curli-positive cells within an E. coli population shows stronger dependence on growth conditions in the absence of regulation by DgcE/PdeH and DgcM/PdeR pairs. We thus conclude that, while not required for the emergence of bimodal curli gene expression in E. coli, this c-di-GMP regulatory network attenuates the frequency and dynamics of gene activation and increases its robustness to cellular heterogeneity and environmental variation.
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Affiliation(s)
- Olga Lamprecht
- Max Planck Institute for Terrestrial Microbiology and Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Maryia Ratnikava
- Max Planck Institute for Terrestrial Microbiology and Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Paulina Jacek
- Max Planck Institute for Terrestrial Microbiology and Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Eugen Kaganovitch
- Max Planck Institute for Terrestrial Microbiology and Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Nina Buettner
- Max Planck Institute for Terrestrial Microbiology and Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Kirstin Fritz
- Max Planck Institute for Terrestrial Microbiology and Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Ina Biazruchka
- Max Planck Institute for Terrestrial Microbiology and Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Robin Köhler
- Max Planck Institute for Terrestrial Microbiology and Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Julian Pietsch
- Max Planck Institute for Terrestrial Microbiology and Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Victor Sourjik
- Max Planck Institute for Terrestrial Microbiology and Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
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Köhler R, Sadhir I, Murray SM. ★Track: Inferred counting and tracking of replicating DNA loci. Biophys J 2023; 122:1577-1585. [PMID: 36966362 PMCID: PMC10183378 DOI: 10.1016/j.bpj.2023.03.033] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 03/10/2023] [Accepted: 03/22/2023] [Indexed: 03/27/2023] Open
Abstract
Fluorescent microscopy is the primary method to study DNA organization within cells. However, the variability and low signal/noise commonly associated with live-cell time-lapse imaging challenges quantitative measurements. In particular, obtaining quantitative or mechanistic insight often depends on the accurate tracking of fluorescent particles. Here, we present ★Track, an inference method that determines the most likely temporal tracking of replicating intracellular particles such DNA loci while accounting for missing, merged, and spurious detections. It allows the accurate prediction of particle copy numbers as well as the timing of replication events. We demonstrate ★Track's abilities and gain new insight into plasmid copy number control and the volume dependence of bacterial chromosome replication initiation. By enabling the accurate tracking of DNA loci, ★Track can help to uncover the mechanistic principles of chromosome organization and dynamics across a range of systems.
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Affiliation(s)
- Robin Köhler
- Max Planck Institute for Terrestrial Microbiology and LOEWE Centre for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Ismath Sadhir
- Max Planck Institute for Terrestrial Microbiology and LOEWE Centre for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Seán M Murray
- Max Planck Institute for Terrestrial Microbiology and LOEWE Centre for Synthetic Microbiology (SYNMIKRO), Marburg, Germany.
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Köhler R, Kaganovitch E, Murray SM. High-throughput imaging and quantitative analysis uncovers the nature of plasmid positioning by ParABS. eLife 2022; 11:78743. [PMID: 36374535 PMCID: PMC9662831 DOI: 10.7554/elife.78743] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 10/23/2022] [Indexed: 11/16/2022] Open
Abstract
The faithful segregation and inheritance of bacterial chromosomes and low-copy number plasmids requires dedicated partitioning systems. The most common of these, ParABS, consists of ParA, a DNA-binding ATPase and ParB, a protein that binds to centromeric-like parS sequences on the DNA cargo. The resulting nucleoprotein complexes are believed to move up a self-generated gradient of nucleoid-associated ParA. However, it remains unclear how this leads to the observed cargo positioning and dynamics. In particular, the evaluation of models of plasmid positioning has been hindered by the lack of quantitative measurements of plasmid dynamics. Here, we use high-throughput imaging, analysis and modelling to determine the dynamical nature of these systems. We find that F plasmid is actively brought to specific subcellular home positions within the cell with dynamics akin to an over-damped spring. We develop a unified stochastic model that quantitatively explains this behaviour and predicts that cells with the lowest plasmid concentration transition to oscillatory dynamics. We confirm this prediction for F plasmid as well as a distantly-related ParABS system. Our results indicate that ParABS regularly positions plasmids across the nucleoid but operates just below the threshold of an oscillatory instability, which according to our model, minimises ATP consumption. Our work also clarifies how various plasmid dynamics are achievable in a single unified stochastic model. Overall, this work uncovers the dynamical nature of plasmid positioning by ParABS and provides insights relevant for chromosome-based systems.
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Affiliation(s)
- Robin Köhler
- Max Planck Institute for Terrestrial Microbiology and LOEWE Centre for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Eugen Kaganovitch
- Max Planck Institute for Terrestrial Microbiology and LOEWE Centre for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Seán M Murray
- Max Planck Institute for Terrestrial Microbiology and LOEWE Centre for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
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Busch J, Kaplan J, Merk T, Köhler R, Neumann W, Kühn A. P 43 Optimizing beta-burst driven adaptive deep brain stimulation for Parkinson's disease. Clin Neurophysiol 2022. [DOI: 10.1016/j.clinph.2022.01.074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ehmann YJ, Berthold DP, Reuter S, Beitzel K, Köhler R, Stöcker F, Muench LN, Pogorzelski J, Rupp MC, Braun S, Imhoff AB, Buchmann S. Center of pressure (COP) measurement in patients with confirmed successful outcomes following shoulder surgery show significant sensorimotor deficits. Knee Surg Sports Traumatol Arthrosc 2022; 30:2060-2066. [PMID: 34741625 PMCID: PMC9165257 DOI: 10.1007/s00167-021-06751-0] [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] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 09/16/2021] [Indexed: 11/27/2022]
Abstract
PURPOSE To determine the sensorimotor and clinical function of patients with confirmed successful outcome after either undergoing acromioclavicular joint (ACJ) stabilization, Bankart repair (BR), or rotator cuff repair (RC), and to compare these measures to the contralateral, healthy side without history of previous injuries or surgeries of the upper extremity. It was hypothesized that patients of each interventional group would have inferior sensorimotor function of the shoulder joint compared to the contralateral, healthy side, while presenting with successful clinical and functional outcomes. METHODS Three intervention groups including ten patients who had confirmed successful clinical and functional outcomes after either undergoing ACJ stabilization, BR, or RC were evaluated postoperatively at an average follow-up of 31.7 ± 11.6 months. Additionally, a healthy control group (CG) of ten patients was included. Clinical outcomes were assessed using the Constant-Murley (CM) and American Shoulder and Elbow Surgeons (ASES) Score. Pain was evaluated using the visual analogue scale (VAS). Sensorimotor function was assessed by determining the center of pressure (COP) of the shoulder joint in a one-handed support task in supine position on a validated pressure plate. RESULTS Each interventional group demonstrated excellent clinical outcome scores including the CM Score (ACJ 83.3 ± 11.8; BR 89.0 ± 10.3; RC 81.4 ± 8.8), ASES Score (ACJ 95.5 ± 7.0; BR 92.5 ± 9.6; RC 96.5 ± 5.2), and VAS (ACJ 0.5 ± 0.9; BR 0.5 ± 0.8; RC 0.5 ± 0.8). Overall, the CG showed no significant side-to-side difference in COP, whereas the ACJ-group and the BR-group demonstrated significantly increased COP compared to the healthy side (ACJ 103 cm vs. 98 cm, p = 0.049; BR: 116 cm vs. 102 cm, p = 0.006). The RC-group revealed no significant side-to-side difference (120 cm vs. 108 cm, n.s.). CONCLUSION Centre of pressure measurement detected sensorimotor functional deficits following surgical treatment of the shoulder joint in patients with confirmed successful clinical and functional outcomes. This may indicate that specific postoperative training and rehabilitation protocols should be established for patients who underwent surgery of the upper extremity. These results underline that sensorimotor training should be an important component of postoperative rehabilitation and physiotherapeutic activities to improve postoperative function and joint control. LEVEL OF EVIDENCE IV.
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Affiliation(s)
- Yannick J Ehmann
- Department of Orthopedic Sports Medicine, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany
| | - Daniel P Berthold
- Department of Orthopedic Sports Medicine, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany
| | - Sven Reuter
- Department of Orthopedic Sports Medicine, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany
- SRH University for Applied Health Sciences, Stuttgart, Germany
| | - Knut Beitzel
- Department of Orthopedic Sports Medicine, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany
- Atos Orthoparc Klinik, Cologne, Germany
| | - Robin Köhler
- Department of Orthopedic Sports Medicine, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany
| | - Fabian Stöcker
- Department of Sport and Health Sciences, TU Munich, Munich, Germany
| | - Lukas N Muench
- Department of Orthopedic Sports Medicine, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany
| | - Jonas Pogorzelski
- Department of Orthopedic Sports Medicine, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany
| | - Marco-Christopher Rupp
- Department of Orthopedic Sports Medicine, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany
| | - Sepp Braun
- Department of Orthopedic Sports Medicine, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany
- Gelenkpunkt, Sport and Joint Surgery Innsbruck, Innsbruck, Austria
- OSMI - Research Unit for Orthopaedic Sports Medicine and Injury Prevention, UMIT - Private University for Health Sciences, Medical Informatics and Technology, Hall, Austria
| | - Andreas B Imhoff
- Department of Orthopedic Sports Medicine, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany.
| | - Stefan Buchmann
- Department of Orthopedic Sports Medicine, Technical University of Munich, Ismaninger Str. 22, 81675, Munich, Germany
- OFZ Weilheim, Weilheim, Germany
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Simonsen U, Wandall-Frostholm C, Oliván-Viguera A, Köhler R. Emerging roles of calcium-activated K channels and TRPV4 channels in lung oedema and pulmonary circulatory collapse. Acta Physiol (Oxf) 2017; 219:176-187. [PMID: 27497091 DOI: 10.1111/apha.12768] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [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: 10/13/2015] [Revised: 11/30/2015] [Accepted: 08/04/2016] [Indexed: 12/12/2022]
Abstract
It has been suggested that the transient receptor potential cation (TRP) channel subfamily V (vanilloid) type 4 (TRPV4) and intermediate conductance calcium-activated potassium (KCa3.1) channels contribute to endothelium-dependent vasodilation. Here, we summarize very recent evidence for a synergistic interplay of TRPV4 and KCa3.1 channels in lung disease. Among the endothelial Ca2+ -permeable TRPs, TRPV4 is best characterized and produces arterial dilation by stimulating Ca2+ -dependent nitric oxide synthesis and endothelium-dependent hyperpolarization. Besides these roles, some TRP channels control endothelial/epithelial barrier functions and vascular integrity, while KCa3.1 channels provide the driving force required for Cl- and water transport in some cells and most secretory epithelia. The three conditions, increased pulmonary venous pressure caused by left heart disease, high inflation pressure and chemically induced lung injury, may lead to activation of TRPV4 channels followed by Ca2+ influx leading to activation of KCa3.1 channels in endothelial cells ultimately leading to acute lung injury. We find that a deficiency in KCa3.1 channels protects against TRPV4-induced pulmonary arterial relaxation, fluid extravasation, haemorrhage, pulmonary circulatory collapse and cardiac arrest in vivo. These data identify KCa3.1 channels as crucial molecular components in downstream TRPV4 signal transduction and as a potential target for the prevention of undesired fluid extravasation, vasodilatation and pulmonary circulatory collapse.
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Affiliation(s)
- U. Simonsen
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology; Aarhus University; Aarhus C Denmark
| | - C. Wandall-Frostholm
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology; Aarhus University; Aarhus C Denmark
| | - A. Oliván-Viguera
- Translational Research Unit; University Hospital Miguel Servet and IACS/IIS; Aragonese Agency for Investigation and Development (ARAID); Zaragoza Spain
| | - R. Köhler
- Translational Research Unit; University Hospital Miguel Servet and IACS/IIS; Aragonese Agency for Investigation and Development (ARAID); Zaragoza Spain
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Köhler R, Oliván-Viguera A, Wulff H. Endothelial Small- and Intermediate-Conductance K Channels and Endothelium-Dependent Hyperpolarization as Drug Targets in Cardiovascular Disease. Advances in Pharmacology 2016; 77:65-104. [DOI: 10.1016/bs.apha.2016.04.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Torge A, Zimmermann M, Möricke A, Köhler R, Alten J, Bartram CR, Schrappe M, Stanulla M. Prediction of minimal residual disease in pediatric ALL: Comparison and evaluation of different mathematical methods applied to data from the ALL-BFM 2000 trial. Klin Padiatr 2014. [DOI: 10.1055/s-0034-1374828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Holzer F, Buchenhorst D, Köhler R, Gaffron A, Weiß H, Kopinke FD, Roland U. Demonstration of In Situ Radio-Frequency Heating at a Former Industrial Site. Chem Eng Technol 2013. [DOI: 10.1002/ceat.201300129] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Torge A, Zimmermann M, Möricke A, Köhler R, Schrauder A, Bartram CR, Schrappe M, Stanulla M. Prediction of minimal residual disease in pediatric ALL: Evaluation of the predictive potential of the variables from the ALL-BFM 2000 trial. Klin Padiatr 2013. [DOI: 10.1055/s-0033-1343620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Torge A, Zimmermann M, Möricke A, Köhler R, Schrauder A, Bartram CR, Schrappe M, Stanulla M. A mathematical approach to data evaluation with focus on prediction of minimal residual disease in pediatric ALL. Klin Padiatr 2012. [DOI: 10.1055/s-0032-1310472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Hasenau AL, Nielsen G, Morisseau C, Hammock BD, Wulff H, Köhler R. Improvement of endothelium-dependent vasodilations by SKA-31 and SKA-20, activators of small- and intermediate-conductance Ca2+ -activated K+ -channels. Acta Physiol (Oxf) 2011; 203:117-26. [PMID: 21362152 DOI: 10.1111/j.1748-1716.2010.02240.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [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: 01/12/2023]
Abstract
AIM Endothelial membrane hyperpolarization mediated by KCa3.1 and KCa2.3 channels has been demonstrated to initiate endothelium-derived hyperpolarizing factor (EDHF)-type vasodilations. Moreover, pharmacological potentiation of KCa3.1/KCa2.3 channels has been suggested to improve EDHF-type vasodilations. Herein, we determined whether the KCa3.1/KCa2.3 activator SKA-31 and its derivative SKA-20 improve endothelial dysfunction in KCa3.1-/- and NOS3-/- mice. METHODS Membrane potentials were measured using patch-clamp electrophysiology on carotid artery (CA) endothelial cells (CAEC) from wild-type (wt) and KCa3.1-/- mice. Endothelium-dependent vasodilations were determined by pressure myography in CA. RESULTS SKA-31 (1 μm) activated KCa3.1 and KCa2.3 channels and induced membrane hyperpolarization in CAEC of wt (ΔMP -45 mV). These responses were significantly reduced in CAEC of KCa3.1-/- (ΔMP -8 mV). SKA-31 (200 nm, 500 nm) and SKA-20 (300 nm) significantly enhanced EDHF vasodilations in wt. SKA-20 also improved vasodilations during NO synthesis. In KCa3.1-/-, the defective EDHF vasodilations were unchanged at 200 nm SKA-31, but were significantly improved at 500 nm. EDHF vasodilations were slightly enhanced at 300 nm SKA-20, but vasodilations during NO synthesis were unchanged. SKA-31 (500 nm) enhanced the impaired endothelium-dependent vasodilation in NOS3-/- mice twofold. Pharmacological inhibition of the soluble epoxide hydrolase by t-AUCB (1 μm) in contrast did not increase ACh-induced EDHF- or NO-mediated vasodilations in wt and KCa3.1-/-. CONCLUSION Normal and defective endothelium-dependent vasodilations in murine carotid arteries can be improved by pharmacological enhancement of KCa3.1/KCa2.3 functions. These findings further support the concept that pharmacological activation of endothelial KCa2.3/KCa3.1 could offer a novel endothelium-specific antihypertensive strategy.
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Affiliation(s)
- A-L Hasenau
- Faculty of Medicine, Philipps University, Marburg, Germany
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Polier G, Ding J, Konkimalla BV, Eick D, Ribeiro N, Köhler R, Giaisi M, Efferth T, Desaubry L, Krammer PH, Li-Weber M. Wogonin and related natural flavones are inhibitors of CDK9 that induce apoptosis in cancer cells by transcriptional suppression of Mcl-1. Cell Death Dis 2011; 2:e182. [PMID: 21776020 PMCID: PMC3199715 DOI: 10.1038/cddis.2011.66] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The wogonin-containing herb Scutellaria baicalensis has successfully been used for curing various diseases in traditional Chinese medicine. Wogonin has been shown to induce apoptosis in different cancer cells and to suppress growth of human cancer xenografts in vivo. However, its direct targets remain unknown. In this study, we demonstrate for the first time that wogonin and structurally related natural flavones, for example, apigenin, chrysin and luteolin, are inhibitors of cyclin-dependent kinase 9 (CDK9) and block phosphorylation of the carboxy-terminal domain of RNA polymerase II at Ser2. This effect leads to reduced RNA synthesis and subsequently rapid downregulation of the short-lived anti-apoptotic protein myeloid cell leukemia 1 (Mcl-1) resulting in apoptosis induction in cancer cells. We show that genetic inhibition of Mcl-1 or CDK9 expression by siRNA is sufficient to mimic flavone-induced apoptosis. Pull-down and in silico docking studies demonstrate that wogonin directly binds to CDK9, presumably to the ATP-binding pocket. In contrast, wogonin does not inhibit CDK2, CDK4 and CDK6 at doses that inhibit CDK9 activity. Furthermore, we show that wogonin preferentially inhibits CDK9 in malignant compared with normal lymphocytes. Thus, our study reveals a new mechanism of anti-cancer action of natural flavones and supports CDK9 as a therapeutic target in oncology.
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Affiliation(s)
- G Polier
- Tumor Immunology Program (D030), German Cancer Research Center (DKFZ), Heidelberg, Germany
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Breithaupt P, Meissner B, Zimmermann M, Möricke A, Schrauder A, Harbott J, Ludwig WD, Köhler R, Bartram CR, Schrappe M, Cario G, Stanulla M. IKZF1 deletion is an independent predictor of outcome in pediatric acute lymphoblastic leukemia treated according to the ALL-BFM 2000 protocol. Klin Padiatr 2011. [DOI: 10.1055/s-0031-1277064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Bleumink M, Köhler R, Giaisi M, Proksch P, Krammer PH, Li-Weber M. Rocaglamide breaks TRAIL resistance in HTLV-1-associated adult T-cell leukemia/lymphoma by translational suppression of c-FLIP expression. Cell Death Differ 2010; 18:362-70. [PMID: 20706274 DOI: 10.1038/cdd.2010.99] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The human T-cell leukemia virus type-1 (HTLV-1)-associated adult T-cell leukemia/lymphoma (ATL) is incurable by currently known therapies. ATL samples and cell lines derived from ATL patients show restricted sensitivity to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and CD95 ligand (CD95L). We have recently shown that HTLV-1-infected cells express elevated levels of cellular caspase-8 FLICE-inhibitory protein (c-FLIP) conferring resistance to receptor-mediated apoptosis. This finding underscores the demand to develop new strategies for treatment of ATL. In this study, we show that the naturally occurring herbal compound Rocaglamide (Roc) sensitizes CD95L- and TRAIL-induced apoptosis in HTLV-1-infected cells by downregulation of c-FLIP expression. Investigation of the molecular mechanism of Roc-mediated downregulation of c-FLIP revealed that it inhibits phosphorylation of the translation initiation factor 4E (eIF4E), a key factor that controls the rate-limiting step of translation, through inhibition of the MEK-ERK-MNK1 signaling pathway. This event prevents de novo synthesis of short-lived proteins such as c-FLIP in HTLV-1-infected cells. Our data suggest that Roc may serve as an adjuvant for TRAIL-based anticancer therapy.
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Affiliation(s)
- M Bleumink
- Tumor Immunology Program, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg, Germany
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Meyberg D, Deuse T, Wulff H, Köhler R, Reichenspurner H, Schrepfer S. Identifying the potassium channel KCa3.1 as new therapeutic target to prevent chronic airway allograft rejection. Thorac Cardiovasc Surg 2010. [DOI: 10.1055/s-0029-1247062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Grgic I, Wulff H, Eichler I, Flothmann C, Köhler R, Hoyer J. Blockade of T-lymphocyte KCa3.1 and Kv1.3 channels as novel immunosuppression strategy to prevent kidney allograft rejection. Transplant Proc 2010; 41:2601-6. [PMID: 19715983 DOI: 10.1016/j.transproceed.2009.06.025] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Currently, there is an unmet clinical need for novel immunosuppressive agents for long-term prevention of kidney transplant rejection as alternatives to the nephrotoxic calcineurin inhibitor cyclosporine (CsA). Recent studies have shown that K(+) channels have a crucial role in T-lymphocyte activity. We investigated whether combined blockade of the T-cell K(+) channels K(Ca)3.1 and K(v)1.3, both of which regulate calcium signaling during lymphocyte activation, is effective in prevention of rejection of kidney allografts from Fisher rats to Lewis rats. All recipients were initially treated with CsA (5 mg/kg d) for 7 days. In rats with intact allograft function, treatment was continued for 10 days with either CsA (5 mg/kg d), or a combination of TRAM-34 (K(Ca)3.1 inhibitor; 120 mg/kg d) plus Stichodactyla helianthus toxin (ShK, K(v)1.3 inhibitor; 80 microg/kg 3 times daily), or vehicle alone. Kidney sections were stained with periodic acid-Schiff or hematoxylin-eosin and histochemically for markers of macrophages (CD68), T-lymphocytes (CD43), or cytotoxic T-cells (CD8). Our results showed that treatment with TRAM-34 and ShK reduced total interstitial mononuclear cell infiltration (-42%) and the number of CD43+ T-cells (-32%), cytotoxic CD8+ T-cells (-32%), and CD68+ macrophages (-26%) in allografts when compared to vehicle treatment alone. Efficacy of TRAM-34/ShK treatment was comparable with that of CsA. In addition, no visible organ damage or other discernible adverse effects were observed with this treatment. Thus, selective blockade of T-lymphocyte K(Ca)3.1 and K(v)1.3 channels may represent a novel alternative therapy for prevention of kidney allograft rejection.
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Affiliation(s)
- I Grgic
- Department of Internal Medicine and Nephrology, University Hospital, Philipps-University, Marburg, Germany
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Edgren J, Köhler R. Urographie mit schneller Injektion großer Kontrastmittelmengen oder als Infusionsurographie. Diagnostischer Wert und Komplikationsfrequenz. ROFO-FORTSCHR RONTG 2009. [DOI: 10.1055/s-0029-1229454] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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21
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Meinhold H, Campos-Barros A, Walzog B, Köhler R, Müller F, Behne D. Effects of selenium and iodine deficiency on type I, type II and type III iodothyronine deiodinases and circulating thyroid hormones in the rat. Exp Clin Endocrinol 2009; 101:87-93. [PMID: 8405144 DOI: 10.1055/s-0029-1211212] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The effects of nutritional selenium (Se) deficiency over a period of three generations and of a combined selenium and iodine deficiency on hepatic and cerebrocortical iodothyronine deiodinases and on circulating thyroid hormone levels were examined in the rat. Se deficiency strongly decreased hepatic type I iodothyronine 5'- and 5-deiodinase to 6-13% of that in controls. Iodine depletion had only a marginal decreasing effect on the type I activity. Cerebrocortical type II 5'-deiodinase was decreased in Se-deficient, iodine-replete rats. Its 5-6-fold elevation in iodine-deficient rats was not reversed by additional selenium deficiency. Cortex type III 5-deiodinase was modestly decreased in all groups with insufficient trace element supply. Long-term Se deficiency has only limited effects on serum T4 and T3 levels. Two months of iodine deficiency decreased serum T4 to less than 10% of that in controls, but did not significantly affect serum T3 levels. The strong decrease of hepatic outer- and inner-ring deiodination of T4 in Se deficiency obviously reflects the reduced tissue concentration of the type I deiodinase which was recently identified as a selenoenzyme. The maintenance of increased cerebrocortical type II deiodinase in iodine-depleted animals irrespective of adequate or deficient selenium supply suggests that the type II isoenzyme does not contain selenium in its catalytic site. Further studies are necessary to clarify whether the weak, but repeatedly confirmed decrease of cortex type III deiodinase is the direct effect of Se deficiency or the indirect consequence of the multilevel change in thyroid hormone metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- H Meinhold
- Department of Nuclear Medicine, Klinikum Steglitz, Free University Berlin, Germany
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22
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Heimbrodt B, Lübbert D, Köhler R, Boeck T, Gerlitzke AK, Hanke M. Analysis of epitaxial laterally overgrown silicon structures by high resolution x-ray rocking curve imaging. Cryst Res Technol 2009. [DOI: 10.1002/crat.200900115] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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23
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Zhu JY, Giaisi M, Köhler R, Müller WW, Mühleisen A, Proksch P, Krammer PH, Li-Weber M. Rocaglamide sensitizes leukemic T cells to activation-induced cell death by differential regulation of CD95L and c-FLIP expression. Cell Death Differ 2009; 16:1289-99. [DOI: 10.1038/cdd.2009.42] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
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24
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Hagedorn N, Schrauder A, Köhler R, zur Stadt U, Seeger K, Henze G, Stackelberg AV, Eckert C. Is measurement of molecular response to therapy in bone marrow useful in children with isolated extramedullary relapse of acute lymphoblastic leukaemia? Klin Padiatr 2009. [DOI: 10.1055/s-0029-1222641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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25
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Schmidbauer M, Schäfer P, Besedin S, Grigoriev D, Köhler R, Hanke M. A novel multi-detection technique for three-dimensional reciprocal-space mapping in grazing-incidence X-ray diffraction. J Synchrotron Radiat 2008; 15:549-557. [PMID: 18955760 DOI: 10.1107/s0909049508023856] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Accepted: 07/28/2008] [Indexed: 05/27/2023]
Abstract
A new scattering technique in grazing-incidence X-ray diffraction geometry is described which enables three-dimensional mapping of reciprocal space by a single rocking scan of the sample. This is achieved by using a two-dimensional detector. The new set-up is discussed in terms of angular resolution and dynamic range of scattered intensity. As an example the diffuse scattering from a strained multilayer of self-assembled (In,Ga)As quantum dots grown on GaAs substrate is presented.
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Affiliation(s)
- M Schmidbauer
- Leibniz Institut für Kristallzüchtung, Max-Born-Strasse 2, D-12489 Berlin, Germany.
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26
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Köhler R, Rutishauser W, Gander M, Babotai I. Veränderungen der Dynamik des linken Ventrikels des Hundes unter paariger Stimulation vor und nach β-Blockade. Cardiology 2008. [DOI: 10.1159/000168924] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Abstract
In the late eighties, several studies revealed the existence of a third vasodilating factor next to nitric oxide (NO) and prostacyclin (PGI2). As the action of this third factor is closely related to smooth muscle hyperpolarization, this factor was termed endothelium-derived hyperpolarizing factor (EDHF). The story of its investigation is a confusing one and several different candidate molecules and pathways have been proposed to account for the EDHF phenomenon. Major candidate molecules/mediators of EDHF signalling are K+, electrical coupling through gap junctions, cytochrome P450 metabolites, and endothelial small- and intermediate Ca2+-activated K+ channels (SK(Ca) and IK(Ca)). In this mini review, we wish to convey that EDHF is as powerful as NO and PGI2 in terms of blood pressure regulation and that deficiency in EDHF signalling contribute to several cardiovascular pathologies such as hypertension, chronic renal failure, and diabetes. In addition, we focus on recent insight into the EDHF phenomenon provided by novel genetic animal models, such as mice deficient of either endothelial SK(Ca) or IK(Ca) and the impact of channel deficiency on endothelial function, EDHF signalling, and arterial blood pressure.
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Affiliation(s)
- R Köhler
- Department of Internal Medicine-Nephrology, Philipps-University, Marburg, Germany.
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29
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Modregger P, Lübbert D, Schäfer P, Köhler R. Phase sensitive micro-tomography with asymmetric Bragg reflection. Acta Crystallogr A 2006. [DOI: 10.1107/s010876730609862x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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30
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Schrauder A, Altmann D, Laude G, Claus H, Wegner K, Köhler R, Habicht-Thomas H, Krause G. Epidemic conjunctivitis in Germany, 2004. Euro Surveill 2006; 11:185-7. [PMID: 16966798] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023] Open
Abstract
Epidemic conjunctivitis can be associated with viral or bacterial pathogens, whereas epidemic keratoconjunctivitis is caused mainly by adenoviruses type 8,19 and 37. In Germany, the incidence of adenovirus conjunctivitis cases increased from 0.2 per 100,000 inhabitants (in 2001 and 2002) eventually to 0.5 in 2003 and 0.8 in 2004. The detection of adenovirus in conjunctival swabs is notifiable to the local health departments. Data about cases with positive conjunctival swabs are then transmitted to the Robert Koch-Institut. Quality control of data takes place and national surveillance data of confirmed cases with adenovirus conjunctivitis are published. From January to April 2004 the national surveillance system captured an outbreak with 1024 cases (131 laboratory confirmed). Analysis of the national surveillance data showed that in March 2004 the group primarily affected by epidemic keratoconjunctivitis was young men between 18-29 years old followed by an increased number of notifications from women in the same age group. Meanwhile the German Armed Forces experienced an outbreak of conjunctivitis, almost exclusively without laboratory confirmation, affecting 6378 soldiers. Despite the small number of laboratory confirmed cases it became clear from the analysis of the national surveillance data that person-to-person transmission between young men and similar age groups of the population did occur. Whether the outbreak started within the garrisons of the German Armed Forces or whether it was triggered within these accommodations, there is clearly a need for the national and the military public health institutions to work together on guidelines to handle future challenges.
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Affiliation(s)
- A Schrauder
- Department for Infectious Disease Epidemiology, Robert Koch-Institut, Berlin, Germany. Field Epidemiology Training Programme, Berlin, Germany
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Abstract
Epidemic conjunctivitis can be associated with viral or bacterial pathogens, whereas epidemic keratoconjunctivitis is caused mainly by adenoviruses type 8,19 and 37. In Germany, the incidence of adenovirus conjunctivitis cases increased from 0.2 per 100 000 inhabitants (in 2001 and 2002) eventually to 0.5 in 2003 and 0.8 in 2004. The detection of adenovirus in conjunctival swabs is notifiable to the local health departments. Data about cases with positive conjunctival swabs are then transmitted to the Robert Koch-Institut. Quality control of data takes place and national surveillance data of confirmed cases with adenovirus conjunctivitis are published. From January to April 2004 the national surveillance system captured an outbreak with 1024 cases (131 laboratory confirmed). Analysis of the national surveillance data showed that in March 2004 the group primarily affected by epidemic keratoconjunctivitis was young men between 18 -29 years old followed by an increased number of notifications from women in the same age group. Meanwhile the German Armed Forces experienced an outbreak of conjunctivitis, almost exclusively without laboratory confirmation, affecting 6378 soldiers.
Despite the small number of laboratory confirmed cases it became clear from the analysis of the national surveillance data that person-to-person transmission between young men and similar age groups of the population did occur. Whether the outbreak started within the garrisons of the German Armed Forces or whether it was triggered within these accommodations, there is clearly a need for the national and the military public health institutions to work together on guidelines to handle future challenges.
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Affiliation(s)
- A Schrauder
- Field Epidemiology Training Programme, Berlin, Germany
- Department for Infectious Disease Epidemiology, Robert Koch-Institut, Berlin, Germany
| | - D Altmann
- Field Epidemiology Training Programme, Berlin, Germany
| | - G Laude
- Department for Infectious Disease Epidemiology, Robert Koch-Institut, Berlin, Germany
| | - H Claus
- Department for Infectious Disease Epidemiology, Robert Koch-Institut, Berlin, Germany
| | - K Wegner
- German Naval Medical Institute, Kiel, Germany
| | - R Köhler
- Medical Office of German Armed Forces, Munich, Germany
| | | | - G Krause
- Federal Ministry of Defence, Bonn, Germany
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Köhler R, Georgi A, Lauenroth S, Kopinke FD. Katalytische Oxidation vs. mikrobiologischer Abbau von Grundwasserkontaminanten unter In-situ-Bedingungen. CHEM-ING-TECH 2006. [DOI: 10.1002/cite.200500097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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33
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Schmidbauer M, Seydmohamadi S, Grigoriev D, Wang ZM, Mazur YI, Schäfer P, Hanke M, Köhler R, Salamo GJ. Controlling planar and vertical ordering in three-dimensional (In,Ga)As quantum dot lattices by GaAs surface orientation. Phys Rev Lett 2006; 96:066108. [PMID: 16606019 DOI: 10.1103/physrevlett.96.066108] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2005] [Indexed: 05/08/2023]
Abstract
Anisotropic surface diffusion and strain are used to explain the formation of three-dimensional (In,Ga)As quantum dot lattices. The diffusion characteristics of the surface, coupled with the elastic anisotropy of the matrix, provides an excellent opportunity to influence the dot positions. In particular, quantum dots that are laterally organized into long chains or chessboard two-dimensional arrays vertically organized with strict vertical ordering or vertical ordering that is inclined to the sample surface normal are accurately predicted and observed.
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Affiliation(s)
- M Schmidbauer
- Institut für Kristallzüchtung, D-12489 Berlin, Germany
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34
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Abstract
Endothelial cation channel are important regulators of vascular tone by modulating intracellular Ca(2+)-signaling and thus adequate synthesis of vasodilating factors. The overall importance of these ion channels suggests that they may represent novel pharmacotherapeutic targets in addition to the well-known voltage-gated calcium channels in vascular smooth muscle. In this short overview we summarize the current knowledge about endothelial ion channels and their roles for endothelium-dependent vasodilatation. Furthermore, we perspectively discuss the usefulness of specific openers of endothelial Ca(2+)-activated K(+)-channels and TRPV-channels as novel antihypertensive drugs.
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Affiliation(s)
- T Maier
- Zentrum für Innere Medizin--Schwerpunkt Nephrologie, Universitätsklinikum der Philipps-Universität Marburg
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35
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Hübers HW, Pavlov S, Semenov A, Köhler R, Mahler L, Tredicucci A, Beere H, Ritchie D, Linfield E. Terahertz quantum cascade laser as local oscillator in a heterodyne receiver. Opt Express 2005; 13:5890-5896. [PMID: 19498595 DOI: 10.1364/opex.13.005890] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Terahertz quantum cascade lasers have been investigated with respect to their performance as a local oscillator in a heterodyne receiver. The beam profile has been measured and transformed in to a close to Gaussian profile resulting in a good matching between the field patterns of the quantum cascade laser and the antenna of a superconducting hot electron bolometric mixer. Noise temperature measurements with the hot electron bolometer and a 2.5 THz quantum cascade laser yielded the same result as with a gas laser as local oscillator.
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36
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van Boekel R, Min M, Leinert C, Waters LBFM, Richichi A, Chesneau O, Dominik C, Jaffe W, Dutrey A, Graser U, Henning T, de Jong J, Köhler R, de Koter A, Lopez B, Malbet F, Morel S, Paresce F, Perrin G, Preibisch T, Przygodda F, Schöller M, Wittkowski M. The building blocks of planets within the 'terrestrial' region of protoplanetary disks. Nature 2004; 432:479-82. [PMID: 15565147 DOI: 10.1038/nature03088] [Citation(s) in RCA: 256] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2004] [Accepted: 10/05/2004] [Indexed: 11/08/2022]
Abstract
Our Solar System was formed from a cloud of gas and dust. Most of the dust mass is contained in amorphous silicates, yet crystalline silicates are abundant throughout the Solar System, reflecting the thermal and chemical alteration of solids during planet formation. (Even primitive bodies such as comets contain crystalline silicates.) Little is known about the evolution of the dust that forms Earth-like planets. Here we report spatially resolved detections and compositional analyses of these building blocks in the innermost two astronomical units of three proto-planetary disks. We find the dust in these regions to be highly crystallized, more so than any other dust observed in young stars until now. In addition, the outer region of one star has equal amounts of pyroxene and olivine, whereas the inner regions are dominated by olivine. The spectral shape of the inner-disk spectra shows surprising similarity with Solar System comets. Radial-mixing models naturally explain this resemblance as well as the gradient in chemical composition. Our observations imply that silicates crystallize before any terrestrial planets are formed, consistent with the composition of meteorites in the Solar System.
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Affiliation(s)
- R van Boekel
- Astronomical Institute Anton Pannekoek, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands.
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37
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Brakemeier S, Si H, Gollasch M, Höffler D, Buhl M, Köhler R, Hoyer J, Eichler I. Dents disease: identification of a novel mutation in the renal chloride channel CLCN5. Clin Nephrol 2004; 62:387-90. [PMID: 15571186 DOI: 10.5414/cnp62387] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Dent's disease is an inherited tubulopathy caused by a mutation in the CLCN5 chloride channel gene. It is characterized by low-molecular weight proteinuria, hypercalciuria, nephrolithiasis or nephrocalcinosis, rickets and eventual-progressive renal failure. Onset of clinical symptoms show a great variability, making a diagnosis at an early stage of the disease often difficult. Given the variably clinical picture, genetic analysis can provide a reliable method to confirm the diagnosis. Here, we report on the case of a patient with progressive renal failure showing signs of a tubular lesion and symptoms of Dent's disease. Although this rare disease was suspected by means of the clinical features, it was genetic analysis that confirmed the diagnosis and revealed a novel mutation in the CLCN5 gene.
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Affiliation(s)
- S Brakemeier
- Department of Nephrology--Charité, Universitätsmedizin Berlin, Germany
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Jaffe W, Meisenheimer K, Röttgering HJA, Leinert C, Richichi A, Chesneau O, Fraix-Burnet D, Glazenborg-Kluttig A, Granato GL, Graser U, Heijligers B, Köhler R, Malbet F, Miley GK, Paresce F, Pel JW, Perrin G, Przygodda F, Schoeller M, Sol H, Waters LBFM, Weigelt G, Woillez J, De Zeeuw PT. The central dusty torus in the active nucleus of NGC 1068. Nature 2004; 429:47-9. [PMID: 15129274 DOI: 10.1038/nature02531] [Citation(s) in RCA: 390] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2004] [Accepted: 04/01/2004] [Indexed: 11/08/2022]
Abstract
Active galactic nuclei (AGNs) display many energetic phenomena--broad emission lines, X-rays, relativistic jets, radio lobes--originating from matter falling onto a supermassive black hole. It is widely accepted that orientation effects play a major role in explaining the observational appearance of AGNs. Seen from certain directions, circum-nuclear dust clouds would block our view of the central powerhouse. Indirect evidence suggests that the dust clouds form a parsec-sized torus-shaped distribution. This explanation, however, remains unproved, as even the largest telescopes have not been able to resolve the dust structures. Here we report interferometric mid-infrared observations that spatially resolve these structures in the galaxy NGC 1068. The observations reveal warm (320 K) dust in a structure 2.1 parsec thick and 3.4 parsec in diameter, surrounding a smaller hot structure. As such a configuration of dust clouds would collapse in a time much shorter than the active phase of the AGN, this observation requires a continual input of kinetic energy to the cloud system from a source coexistent with the AGN.
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Affiliation(s)
- W Jaffe
- Leiden Observatory, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands.
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Altin D, Härtwig J, Köhler R, Ludwig W, Ohler M, Klein H. X-ray diffraction topography using a diffractometer with a bendable monochromator at a synchrotron radiation source. J Synchrotron Radiat 2002; 9:282-286. [PMID: 12200570 DOI: 10.1107/s0909049502010294] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2002] [Accepted: 06/10/2002] [Indexed: 05/23/2023]
Abstract
The different properties of laboratory- and synchrotron-based double-crystal setups for X-ray topographic applications are discussed as a basis for the realization of a versatile instrument allowing the investigation of all kinds of crystals with high strain sensitivity and without any reduction in image size. It appears that the use of a bendable highly perfect monochromator (silicon) achieves this goal, through the local adaptation of Bragg angles, to compensate either dispersion or a bending of the sample.
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Affiliation(s)
- D Altin
- European Synchrotron Radiation Facility (ESRF), Grenoble, France
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Stannarius R, Köhler R, Dietrich U, Lösche M, Tolksdorf C, Zentel R. Structure and elastic properties of smectic liquid crystalline elastomer films. Phys Rev E Stat Nonlin Soft Matter Phys 2002; 65:041707. [PMID: 12005846 DOI: 10.1103/physreve.65.041707] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2001] [Indexed: 05/23/2023]
Abstract
Mechanical measurements, x-ray investigations, and optical microscopy are employed to characterize the interplay of chemical composition, network topology, and elastic response of smectic liquid crystalline elastomers (LCEs) in various mesophases. Macroscopically ordered elastomer films of submicrometer thicknesses were prepared by cross linking freely suspended smectic polymer films. The cross-linked material preserves the mesomorphism and phase transitions of the precursor polymer. The elastic response of the smectic LCE is entropic, and the corresponding elastic moduli are of the order of MPa. In the tilted ferroelectric smectic-C* phase, the network structure plays an important role. Due to the coupling of elastic network deformations to the orientation of the mesogenic groups in interlayer cross-linked materials (mesogenic cross-linker units), the stress-strain characteristics is found to differ qualitatively from that in the other phases.
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Affiliation(s)
- R Stannarius
- Institut für Experimentalphysik I, Universität Leipzig, Linnéstrasse 5, D-04103 Leipzig, Germany
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Köhler R, Brakemeier S, Kühn M, Behrens C, Real R, Degenhardt C, Orzechowski HD, Pries AR, Paul M, Hoyer J. Impaired hyperpolarization in regenerated endothelium after balloon catheter injury. Circ Res 2001; 89:174-9. [PMID: 11463725 DOI: 10.1161/hh1401.093460] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Ca(2+)-activated K(+) (K(Ca)) channels control endothelial Ca(2+) homeostasis and the formation of vasodilators. After angioplasty, dysfunction of the regenerated endothelium leads to abnormal vasoregulation. In this study, we tested the expression and function of K(Ca) channels in regenerated endothelium at 6 weeks after balloon catheter injury of rat carotid arteries (CAs) by using single-cell reverse transcription-polymerase chain reaction, patch-clamp techniques, and analysis of vasoreactivity. In single regenerated endothelial cells (ECs), the percentage of ECs expressing the K(Ca) genes, rSK3 (12+/-8%) and rIK1 (22+/-9%), was significantly lower compared with the percentage of native ECs expressing these genes (rSK3 58+/-8%, rIK1 64+/-10%). In patch-clamp experiments, K(Ca) currents and acetylcholine-induced hyperpolarization were markedly reduced in regenerated ECs (shift of membrane potential -6+/-3 mV) compared with those in native ECs (shift of membrane potential -21+/-5 mV). In pressure myograph experiments, acetylcholine-induced dilation was impaired in reendothelialized CAs compared with normal CAs. Intraluminal application of the K(Ca) blocker apamin and charybdotoxin inhibited dilation by 30% in normal CAs but was without effect in reendothelialized CAs. Intraluminal application of 1-ethyl-2-benzimidazolinone (100 micromol/L), an opener of K(Ca) channels, evoked dilation by 29% in normal CAs but had no effect in reendothelialized CAs. In conclusion, the impaired expression of K(Ca) channels in regenerated endothelium results in defective hyperpolarization and impaired dilation. Thus, the impaired K(Ca) channel function contributes to functional alterations of regenerated endothelium after angioplasty.
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Affiliation(s)
- R Köhler
- Department of Nephrology, Benjamin Franklin Medical Center, and the Institute for Physiology, Freie Universität, Berlin, Germany.
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Köhler R, Grundig A, Brakemeier S, Rothermund L, Distler A, Kreutz R, Hoyer J. Regulation of pressure-activated channel in intact vascular endothelium of stroke-prone spontaneously hypertensive rats. Am J Hypertens 2001; 14:716-21. [PMID: 11465659 DOI: 10.1016/s0895-7061(01)01306-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The pressure-activated cation channel (PAC), a novel type of mechanosensitive channel, has been suggested to act as a mechanosensor in aortic endothelium. In experimental hypertension, PAC function was up-regulated in the established phase of high blood pressure. This association of altered PAC function and elevated arterial pressure suggests that PAC function is regulated by alterations in blood pressure. In the present study, we electrophysiologically investigated PAC function in intact endothelium of aorta (EA) and mesenteric artery (EMA) from stroke-prone spontaneously hypertensive rats (SHRSP), SHRSP after 4 weeks of treatment with quinaprilat (10 mg/kg/day), and normotensive Wistar-Kyoto (WKY) rats. In untreated SHRSP and WKY rats, systolic blood pressure (SBP) was 201+/-3 mm Hg and 142+/-3 mm Hg, respectively. In quinaprilat-treated SHRSP, SBP was lowered to 135+/-5 mm Hg. Apparent PAC density (percentage of patches with PAC activity) in EA of untreated SHRSP (63.7%+/-7.3%) was 2.4-fold higher than in WKY rats (26.0%+/-5.0%). In contrast, no significant PAC up-regulation was detected in EMA of SHRSP (15.7%+/-4.2%) compared with WKY rats (12.0%+/-3.9%). In EA of quinaprilat-treated normotensive SHRSP, PAC density (27.1%+/-5.2%) was lowered to levels found in normotensive WKY rats. Unitary conductance and pressure sensitivity of PAC were not altered in either hypertensive or normotensive rats. Taken together, hypertension-induced increases of endothelial PAC density can be completely reversed by antihypertensive therapy. The PAC up-regulation in EA was interpreted as a compensatory mechanism to enhance Ca2+-influx and subsequently the synthesis of vasodilatory factors. This mechanism is missing in EMA of SHRSP, which might contribute to high blood pressure in this rat model of severe genetic hypertension.
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Affiliation(s)
- R Köhler
- Department of Nephrology, University Hospital Benjamin Franklin, Freie Universität Berlin, Germany
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Köhler R, Brakemeier S, Kühn M, Degenhardt C, Buhr H, Pries A, Hoyer J. Expression of ryanodine receptor type 3 and TRP channels in endothelial cells: comparison of in situ and cultured human endothelial cells. Cardiovasc Res 2001; 51:160-8. [PMID: 11399258 DOI: 10.1016/s0008-6363(01)00281-4] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
OBJECTIVE Ca(2+) mobilization plays an important role in endothelial function by stimulating Ca(2+)-dependent synthesis of vasodilating factors. In addition to inositol-1,4,5-trisphosphate (InsP(3)) mediated Ca(2+) mobilization, Ca(2+) release from ryanodine-sensitive pools and Ca(2+)-influx through TRP channels have been suggested to be important in endothelial Ca(2+)-signaling. However, the function and molecular identity of TRP channels and ryanodine receptors in human endothelium in situ are still elusive. We hypothesized that expression of ryanodine-receptors (RyR) and TRP channels differs between human endothelium in situ and in cultured cells. METHODS By combining single-cell RT-PCR and patch-clamp techniques, expression of RyR and TRP channels was determined in situ in endothelial cells of human mesenteric artery (HMAECs) obtained from patients undergoing bowel resection and in the endothelial cell line EA.hy926. RESULTS At the single cell level, expression of RyR 3 was detected in 25 and 5% of HMAECs and EA.hy926 samples, respectively. Expression of the RyR 1 and 2 was not detected in either HMAECs or EA.hy926. In patch-clamp experiments in HMAECs, applications of caffeine (0.5 mM) induced sustained hyperpolarization mediated by activation of Ca(2+)-activated K channels. In EA.hy926, caffeine-induced hyperpolarization was not detected. Single HMAECs expressed the TRP genes, TRP1 and TRP3, but not TRP 4 and 6. The TRP1 was the predominantly expressed TRP gene in HMAECs in situ whereas TRP3 expression was rarely detected. EA.hy926 expressed only TRP1. In patch clamp experiments in HMAECs, Ca(2+)-store depletion activated non-selective cation currents leading to Ca(2+) entry. CONCLUSIONS Our findings suggest that, in addition to InsP(3) mediated Ca(2+) release, Ca(2+) release from ryanodine-sensitive stores mediated by RyR3 and Ca(2+) entry through TRP1 might represent important components of endothelial Ca(2+) signaling in situ and thereby of endothelial function in intact human blood vessels.
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Affiliation(s)
- R Köhler
- Department of Endocrinology and Nephrology, Medical Center Benjamin Franklin, Freie Universität Berlin, Berlin, Germany.
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Köhler R, Degenhardt C, Kühn M, Runkel N, Paul M, Hoyer J. Expression and function of endothelial Ca(2+)-activated K(+) channels in human mesenteric artery: A single-cell reverse transcriptase-polymerase chain reaction and electrophysiological study in situ. Circ Res 2000; 87:496-503. [PMID: 10988242 DOI: 10.1161/01.res.87.6.496] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Ca(2+)-activated K(+) (K(Ca)) channels have been suggested to play a role in the control of endothelial functions such as regulation of vascular tone and cell proliferation. We established a method for single-cell reverse transcriptase-polymerase chain reaction analysis in combination with the patch-clamp technique to characterize K(Ca) channel expression and function in single endothelial cells (ECs) within the endothelial monolayer of intact human mesenteric arteries (MAs) and in disease states. We tested whether endothelial K(Ca) channel expression and function are altered in MAs obtained from patients with colonic adenocarcinoma (CA) compared with those in MAs from non-cancer patients with inactive diverticulitis. Expression of the intermediate-conductance K(Ca) channel (hIK1) was detected in non-cancer and CA patients. In whole-cell patch-clamp measurements, only ECs expressing hIK1 exhibited corresponding K(Ca) currents, whereas respective K(Ca) currents were missing in hIK1-negative ECs. This heterogeneity of hIK1 expression patterns is indicative of a specialized subset of ECs within the endothelial monolayer. In CA patients, compared with non-cancer patients, a 2.5-fold increase in hIK1-expressing ECs per MA was observed (P:<0.05). However, K(Ca) current densities in hIK1-expressing ECs of both groups were similar. In addition to hIK1, expression of the large-conductance K(Ca) channel (hSlo) was detected in single ECs from CA patients. The increased K(Ca) channel expression in CA patients resulted in a 2. 7-fold increase of bradykinin-induced endothelial hyperpolarization compared with controls (P:<0.05). This increased expression and function of K(Ca) channels might indicate an altered functional state of the endothelium in cancer patients and could play a role in tumor angiogenesis.
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Affiliation(s)
- R Köhler
- Department of Nephrology, Benjamin Franklin Medical Center, Freie Universität, Berlin, Germany
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Löhr F, Pérez C, Köhler R, Rüterjans H, Schmidt JM. Heteronuclear relayed E.COSY revisited: determination of 3J(H(alpha),C(gamma)) couplings in Asx and aromatic residues in proteins. J Biomol NMR 2000; 18:13-22. [PMID: 11061224 DOI: 10.1023/a:1008385202639] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Constant-time 3D heteronuclear relayed E.COSY [Schmidt et al. (1996) J. Biomol. NMR, 7, 142-152], as based on generic 2D small-flip-angle HMQC-COSY [Schmidt et al. (1995) J. Biomol. NMR, 6, 95-105], has been modified to allow for quantitative determination of heteronuclear three-bond 3J(H(alpha),C(gamma)) couplings. The method is applicable to amino acid spin topologies with carbons in the gamma position which lack attached protons, i.e. to asparagine, aspartate, and aromatic residues in uniformly 13C-enriched proteins. The pulse sequence critically exploits heteronuclear triple-quantum coherence (HTQC) of CH2 moieties involving geminal H(beta) proton pairs, taking advantage of improved multiple-quantum relaxation properties, at the same time avoiding scalar couplings between those spins involved in multiple-quantum coherence, thus yielding E.COSY-type multiplets with a splitting structure that is simpler than with the original scheme. Numerical least-squares 2D line-shape simulation is used to extract 3J(H(alpha),C(gamma)) coupling constants which are of relevance to side-chain chi1 dihedral-angle conformations in polypeptides. Methods are demonstrated with recombinant 15N,13C-enriched ribonuclease T1 and Desulfovibrio vulgaris flavodoxin with bound oxidized FMN.
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Affiliation(s)
- F Löhr
- Institut für Biophysikalische Chemie, Johann Wolfgang Goethe-Universität, Biozentrum N230, Frankfurt am Main, Germany
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Hilgenfeld R, Vogel A, Hacker J, Köhler R, Fischer G, König B, Riboldi-Tunnicliffe A. Towards understanding bacterial virulence:The first crystal structure of a Legionellaprotein. Acta Crystallogr A 2000. [DOI: 10.1107/s0108767300022649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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