FMP Publications

Our publications are recorded in a searchable database since 2010, updates will be added regularly.

Year:  
All :: 2010, 2011, 2012, 2013, ... , 2017
Author:  
All :: (, A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z 
Preferences: 
References per page: Show keywords Show abstracts
References
Antigen 85C inhibition restricts Mycobacterium tuberculosis growth through disruption of cord factor biosynthesis
Warrier(*), T., Tropis(*), M., Werngren(*), J., Diehl, A., Gengenbacher(*), M., Schlegel, B., Schade(*), M., Oschkinat, H., Daffe(*), M., Hoffner(*), S., Eddine(*), A. N.; Kaufmann(*), S. H.
Antimicrob Agents Chemother, 56:1735-1743
(2012)

Tags: NMR-Supported Structural Biology (Oschkinat), Solution NMR (Schmieder)

Abstract: The antigen 85 (Ag85) protein family, consisting of Ag85A, -B, and -C, is vital for Mycobacterium tuberculosis due to its role in cell envelope biogenesis. The mycoloyl transferase activity of these proteins generates trehalose dimycolate (TDM), an envelope lipid essential for M. tuberculosis virulence, and cell wall arabinogalactan-linked mycolic acids. Inhibition of these enzymes through substrate analogs hinders growth of mycobacteria, but a link to mycolic acid synthesis has not been established. In this study, we characterized a novel inhibitor of Ag85C, 2-amino-6-propyl-4,5,6,7-tetrahydro-1-benzothiophene-3-carbonitrile (I3-AG85). I3-AG85 was isolated from a panel of four inhibitors that exhibited structure- and dose-dependent inhibition of M. tuberculosis division in broth culture. I3-AG85 also inhibited M. tuberculosis survival in infected primary macrophages. Importantly, it displayed an identical MIC against the drug-susceptible H37Rv reference strain and a panel of extensively drug-resistant/multidrug-resistant M. tuberculosis strains. Nuclear magnetic resonance analysis indicated binding of I3-AG85 to Ag85C, similar to its binding to the artificial substrate octylthioglucoside. Quantification of mycolic acid-linked lipids of the M. tuberculosis envelope showed a specific blockade of TDM synthesis. This was accompanied by accumulation of trehalose monomycolate, while the overall mycolic acid abundance remained unchanged. Inhibition of Ag85C activity also disrupted the integrity of the M. tuberculosis envelope. I3-AG85 inhibited the division of and reduced TDM synthesis in an M. tuberculosis strain deficient in Ag85C. Our results indicate that Ag85 proteins are promising targets for novel antimycobacterial drug design.

Coumarin-based octopamine phototriggers and their effects on an insect octopamine receptor
Schaal, J., Dekowski, B., Wiesner, B., Eichhorst, J., Marter(*), K., Vargas(*), C., Keller(*), S., Eremina(*), N., Barth(*), A., Baumann(*), A., Eisenhardt(*), D.; Hagen, V.
Chembiochem, 13:1458-1464
(2012)

Tags: Synthetic Organic Biochemistry (Hagen), Cellular Imaging (Wiesner)

Abstract: We have developed and characterized efficient caged compounds of the neurotransmitter octopamine. For derivatization, we introduced [6-bromo-8-(diethylaminomethyl)-7-hydroxycoumarin-4-yl]methoxycarbonyl (DBHCMOC) and 6-bromo-7-hydroxy-8-[(piperazin-1-yl)methyl]coumarin-4-ylmethoxycarbonyl (PBHCMOC) moieties as novel photo-removable protecting groups. The caged compounds were functionally inactive when applied to heterologously expressed octopamine receptors (AmOctalpha1R). Upon irradiation with UV-visible or IR light, bioactive octopamine was released and evoked Ca2+ signals in AmOctalpha1R-expressing cells. The pronounced water solubility of compounds 2-4 in particular holds great promise for these substances as excellent phototriggers of this important neurotransmitter.

In-cell NMR in mammalian cells: part 1
Bekei, B., Rose, H. M., Herzig, M., Dose, A., Schwarzer, D.; Selenko, P.
Methods Mol Biol, 895:43-54
(2012)

Tags: In-Cell NMR (Selenko), Protein Chemistry (Schwarzer)

Abstract: Many mammalian IDPs exert important biological functions in key cellular processes and often in highly specialized subsets of cells. For these reasons, tools to characterize the structural and functional characteristics of IDPs inside mammalian cells are of particular interest. Moving from bacterial and amphibian in-cell NMR experiments to mammalian systems offers the unique opportunity to advance our knowledge about general IDP properties in native cellular environments. This is never more relevant than for IDPs that exhibit pathological structural rearrangements under certain cellular conditions, as is the case for human alpha-synuclein in dopaminergic neurons of the substantia nigra in the course of Parkinson's disease, for example. To efficiently deliver isotope-labeled IDPs into mammalian cells is one of the first challenges when preparing a mammalian in-cell NMR sample. The method presented here provides a detailed protocol for the transduction of isotope-labeled alpha-synuclein, as a model IDP, into cultured human HeLa cells. Cellular IDP delivery is afforded by action of a cell-penetrating peptide (CPP) tag. In the protocol outlined below, the CPP tag is "linked" to the IDP cargo moiety via an oxidative, disulfide-coupling reaction.

Structural properties of EGCG-induced, nontoxic Alzheimer's disease Abeta oligomers
Lopez del Amo, J. M., Fink, U., Dasari, M., Grelle(*), G., Wanker(*), E. E., Bieschke(*), J.; Reif, B.
J Mol Biol, 421:517-524
(2012)

Tags: Solid-State NMR Spectroscopy (Reif)

Abstract: The green tea compound epigallocatechin-3-gallate (EGCG) inhibits Alzheimer's disease beta-amyloid peptide (Abeta) neurotoxicity. Solution-state NMR allows probing initial EGCG-Abeta interactions. We show that EGCG-induced Abeta oligomers adopt a well-defined structure and are amenable for magic angle spinning solid-state NMR investigations. We find that EGCG interferes with the aromatic hydrophobic core of Abeta. The C-terminal part of the Abeta peptide (residues 22-39) adopts a beta-sheet conformation, whereas the N-terminus (residues 1-20) is unstructured. The characteristic salt bridge involving residues D23 and K28 is present in the structure of these oligomeric Abeta aggregates as well. The structural analysis of small-molecule-induced amyloid aggregates will open new perspectives for Alzheimer's disease drug development.

An Asymmetric Dimer as the Basic Subunit in Alzheimer's Disease Amyloid beta Fibrils
Lopez del Amo, J. M., Schmidt(*), M., Fink, U., Dasari, M., Fändrich(*), M.; Reif, B.
Angew Chem Int Edit, 51:6136-6139
(2012)

Tags: Solid-State NMR Spectroscopy (Reif)

Mode of action of cationic antimicrobial peptides defines the tethering position and the efficacy of biocidal surfaces
Bagheri, M., Beyermann, M.; Dathe, M.
Bioconjug Chem, 23:66-74
(2012)

Tags: Peptide-Lipid-Interaction/ Peptide Transport (Dathe), Peptide Chemistry (Beyermann)

Abstract: Covalent immobilization of cationic antimicrobial peptides (CAPs) at sufficient density and distance from the solid matrix has been suggested as a successful strategy for the generation of biocidal surfaces. To test the hypothesis that the mode of peptide action is decisive for the selection of an appropriate tethering position on solid surfaces, melittin (MEL), a channel-forming peptide, buforin 2 (BUF2), a peptide able to translocate bacterial membranes without permeabilization and targeting nucleic acids, and tritrpticin (TP), described to be membrane-lytic and to have intracellular targets, were C- and N-terminally immobilized on TentaGel S NH(2) resin beads as model surface. The peptide termini were modified with aminooxyacetic acid (AOA) and coupled via oxime-forming ligation. The comparison of the activities of the three peptides and their AOA-modified analogues with a KLAL model peptide which permeabilizes membranes by a so-called "carpet-like" mode provided the following results: The peptides in solution state were active against Bacillus subtilis and Escherichia coli at micromolar concentrations. MEL and TP but not BUF2-derived peptides permeabilized the inner and outer membrane of E. coli and enhanced the permeability of lipid bilayers at concentrations around their antimicrobial values (MICs). Immobilization reduced peptide activity to millimolar MICs. The activity reduction for KLAL was independent of the tethering position and comparably low, as reflected by a low ratio of MIC(tethered)/MIC(free). In contrary, the pore-forming MEL was much less active when immobilized at the N-terminus compared with the C-terminally tethered peptide. C- and N-terminal TP tethering caused an identical but much pronounced activity decrease. The tethered BUF2 peptides were inactive at the tested concentrations suggesting that the peptides could not reach the intracellular targets. In conclusion, membrane active peptides seem to be most suitable for the generation of antimicrobial surfaces, but knowledge about their mode of membrane insertion and positioning is required to identify optimal tethering positions. The relationship between the mechanism of action and position of immobilization is highly relevant for the establishment of a general approach to obtain efficient biocidal solid matrices loaded with CAPs.

Mode of action of cationic antimicrobial peptides defines the tethering position and the efficacy of biocidal surfaces
Bagheri, M., Beyermann, M.; Dathe, M.
Bioconjug Chem, 23:66-74
(2012)

Tags: Peptide Chemistry (Beyermann),Peptide-Lipide-Interaction (Dathe)

Abstract: Covalent immobilization of cationic antimicrobial peptides (CAPs) at sufficient density and distance from the solid matrix has been suggested as a successful strategy for the generation of biocidal surfaces. To test the hypothesis that the mode of peptide action is decisive for the selection of an appropriate tethering position on solid surfaces, melittin (MEL), a channel-forming peptide, buforin 2 (BUF2), a peptide able to translocate bacterial membranes without permeabilization and targeting nucleic acids, and tritrpticin (TP), described to be membrane-lytic and to have intracellular targets, were C- and N-terminally immobilized on TentaGel S NH(2) resin beads as model surface. The peptide termini were modified with aminooxyacetic acid (AOA) and coupled via oxime-forming ligation. The comparison of the activities of the three peptides and their AOA-modified analogues with a KLAL model peptide which permeabilizes membranes by a so-called "carpet-like" mode provided the following results: The peptides in solution state were active against Bacillus subtilis and Escherichia coli at micromolar concentrations. MEL and TP but not BUF2-derived peptides permeabilized the inner and outer membrane of E. coli and enhanced the permeability of lipid bilayers at concentrations around their antimicrobial values (MICs). Immobilization reduced peptide activity to millimolar MICs. The activity reduction for KLAL was independent of the tethering position and comparably low, as reflected by a low ratio of MIC(tethered)/MIC(free). In contrary, the pore-forming MEL was much less active when immobilized at the N-terminus compared with the C-terminally tethered peptide. C- and N-terminal TP tethering caused an identical but much pronounced activity decrease. The tethered BUF2 peptides were inactive at the tested concentrations suggesting that the peptides could not reach the intracellular targets. In conclusion, membrane active peptides seem to be most suitable for the generation of antimicrobial surfaces, but knowledge about their mode of membrane insertion and positioning is required to identify optimal tethering positions. The relationship between the mechanism of action and position of immobilization is highly relevant for the establishment of a general approach to obtain efficient biocidal solid matrices loaded with CAPs.

Sodium caprate transiently opens claudin-5-containing barriers at tight junctions of epithelial and endothelial cells
Del Vecchio, G., Tscheik, C., Tenz, K., Helms(*), H. C., Winkler, L., Blasig, R.; Blasig, I. E.
Mol Pharm, 9:2523-2533
(2012)

Tags: Molecular Cell Physiology (Blasig, I.E.)

Abstract: Claudin-5 is a tight junction (TJ) protein which limits the diffusion of small hydrophilic molecules. Thus, it represents a potential pharmacological target to improve drug delivery to the tissues protected by claudin-5-dependent barriers. Sodium caprate is known as an absorption enhancer which opens the paracellular space acting on TJ proteins and actin cytoskeleton. Its action on claudin-5 is not understood so far. Epithelial and endothelial systems were used to evaluate the effect of caprate on claudin-5 in TJ-free cells and on claudin-5 fully integrated in TJ. To this aim, confocal microscopy on live and fixed cells and isolated mouse brain capillaries, Western blotting and permeability assays were employed. Caprate reversibly reduced claudin-5 trans-interactions in TJ-free human embryonic kidney-293 cells expressing claudin-5-YFP. It decreased the membranous claudin-5 and the F-actin content in Madin-Darby canine kidney-II cells expressing Flag-claudin-5, thereby increasing the permeability to the small molecule lucifer yellow. Interestingly, zonula occludens protein 1 (ZO-1), which links transmembranous TJ proteins to the actin cytoskeleton, was not affected by caprate treatment. Similarly, endogenous claudin-5 in the membrane of brain endothelia was displaced together with F-actin, whereas ZO-1 remained unaffected. Caprate transiently opens the paracellular space, reducing the intercellular claudin-5/claudin-5 interactions and the polymerized actin at the perijunctional region of endothelial and epithelial cells. In conclusion, the study further elucidates the cellular effects of caprate at the tight junctions.

Optimized Use of Reversible Binding for Fast and Selective NMR Localization of Caged Xenon
Kunth, M., Döpfert, J., Witte, C., Rossella, F.; Schröder, L.
Angew Chem Int Edit, 51:8217-8220
(2012)

Tags: Molecular Imaging (Schröder)

Hyperpolarized xenon for NMR and MRI applications
Witte, C., Kunth, M., Döpfert, J., Rossella, F.; Schröder, L.
J Vis Exp,
(2012)

Tags: Molecular Imaging (Schröder)

Abstract: Nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) suffer from intrinsic low sensitivity because even strong external magnetic fields of ~10 T generate only a small detectable net-magnetization of the sample at room temperature (1). Hence, most NMR and MRI applications rely on the detection of molecules at relative high concentration (e.g., water for imaging of biological tissue) or require excessive acquisition times. This limits our ability to exploit the very useful molecular specificity of NMR signals for many biochemical and medical applications. However, novel approaches have emerged in the past few years: Manipulation of the detected spin species prior to detection inside the NMR/MRI magnet can dramatically increase the magnetization and therefore allows detection of molecules at much lower concentration (2). Here, we present a method for polarization of a xenon gas mixture (2-5% Xe, 10% N2, He balance) in a compact setup with a ca. 16000-fold signal enhancement. Modern line-narrowed diode lasers allow efficient polarization (7) and immediate use of gas mixture even if the noble gas is not separated from the other components. The SEOP apparatus is explained and determination of the achieved spin polarization is demonstrated for performance control of the method. The hyperpolarized gas can be used for void space imaging, including gas flow imaging or diffusion studies at the interfaces with other materials (8,9). Moreover, the Xe NMR signal is extremely sensitive to its molecular environment (6). This enables the option to use it as an NMR/MRI contrast agent when dissolved in aqueous solution with functionalized molecular hosts that temporarily trap the gas (10,11). Direct detection and high-sensitivity indirect detection of such constructs is demonstrated in both spectroscopic and imaging mode.

Page:  
Previous | 1, 2 | Next
Export as:
BibTeX, XML

Leibniz-Forschungsinstitut für Molekulare Pharmakologie im Forschungsverbund Berlin e.V. (FMP)
Campus Berlin-Buch
Robert-Roessle-Str. 10
13125 Berlin, Germany
+4930 94793 - 100 
+4930 94793 - 109 (Fax)
info(at)fmp-berlin.de

Like many sites, we use cookies to optimize the user's browsing experience. Data Protection OK