FMP Publications

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

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References
Glycoprotein B of equine herpesvirus type 1 has two recognition sites for subtilisin-like proteases that are cleaved by furin
Spiesschaert(*), B., Stephanowitz, H., Krause, E., Osterrieder(*), N.; Azab(*), W.
J Gen Virol, 97:1218-1228
(2016)

Tags: Mass Spectrometry (Krause, E.)

Abstract: Glycoprotein B (gB) of equine herpesvirus type 1 (EHV-1) is predicted to be cleaved by furin in a fashion similar to that of related herpesviruses. To investigate the contribution of furin-mediated gB cleavage to EHV-1 growth, canonical furin cleavage sites were mutated. Western blot analysis of mutated EHV-1 gB showed that it was cleaved at two positions, 518RRRR521 and 544RLHK547, and that the 28 aa between the two sites were removed after cleavage. Treating infected cells with either convertase or furin inhibitors reduced gB cleavage efficiency. Further, removal of the first furin recognition motif did not affect in vitro growth of EHV-1, while mutation of the second motif greatly affected virus growth. In addition, a second possible signal peptide cleavage site was identified for EHV-1 gB between residues 98 and 99, which was 13 aa downstream of that previously identified.

Cannabinoid Type 2 Receptors Mediate a Cell Type-Specific Plasticity in the Hippocampus
Stempel(*), A. V., Stumpf(*), A., Zhang(*), H. Y., Ozdogan(*), T., Pannasch(*), U., Theis(*), A. K., Otte(*), D. M., Wojtalla(*), A., Racz(*), I., Ponomarenko, A., Xi(*), Z. X., Zimmer(*), A.; Schmitz(*), D.
Neuron, 90:795-809
(2016)

Tags: Behavioral Neurodynamics (Korotkova/Ponomarenko)

Abstract: Endocannabinoids (eCBs) exert major control over neuronal activity by activating cannabinoid receptors (CBRs). The functionality of the eCB system is primarily ascribed to the well-documented retrograde activation of presynaptic CB1Rs. We find that action potential-driven eCB release leads to a long-lasting membrane potential hyperpolarization in hippocampal principal cells that is independent of CB1Rs. The hyperpolarization, which is specific to CA3 and CA2 pyramidal cells (PCs), depends on the activation of neuronal CB2Rs, as shown by a combined pharmacogenetic and immunohistochemical approach. Upon activation, they modulate the activity of the sodium-bicarbonate co-transporter, leading to a hyperpolarization of the neuron. CB2R activation occurred in a purely self-regulatory manner, robustly altered the input/output function of CA3 PCs, and modulated gamma oscillations in vivo. To conclude, we describe a cell type-specific plasticity mechanism in the hippocampus that provides evidence for the neuronal expression of CB2Rs and emphasizes their importance in basic neuronal transmission.

Dynamic Nuclear Polarization Provides New Insights into Chromophore Structure in Phytochrome Photoreceptors
Stöppler, D., Song(*), C., van Rossum, B. J., Geiger, M. A., Lang(*), C., Mroginski(*), M. A., Jagtap(*), A. P., Sigurdsson(*), S. T., Matysik(*), J., Hughes(*), J.; Oschkinat, H.
Angew Chem Int Ed Engl, 55:16017-16020
(2016)

Tags: NMR-Supported Structural Biology (Oschkinat)

Abstract: Phytochromes are red/far-red photochromic photoreceptors acting as master regulators of development in higher plants, thereby controlling transcription of about 20 % of their genes. Light-induced isomerization of the bilin chromophore leads to large rearrangements in protein structure, whereby the role of protonation dynamics and charge distribution is of particular interest. To help unravel the inherent mechanisms, we present two-dimensional dynamic nuclear polarization (DNP) enhanced solid-state magic-angle spinning (MAS) NMR spectra of the functional sensory module of the cyanobacterial phytochrome Cph1. To this end, the pyrrole ring nitrogen signals were assigned unequivocally, enabling us to locate the positive charge of the phycocyanobilin (PCB) chromophore. To help analyze proton exchange pathways, the proximity of PCB ring nitrogen atoms and functionally relevant H2 O molecules was also determined. Our study demonstrates the value of DNP in biological solid-state MAS NMR spectroscopy.

Modulations of DNA Contacts by Linker Histones and Post-translational Modifications Determine the Mobility and Modifiability of Nucleosomal H3 Tails
Stützer(*), A., Liokatis, S., Kiesel(*), A., Schwarzer, D., Sprangers(*), R., Söding(*), J., Selenko, P.; Fischle(*), W.
Mol Cell, 61:247-259
(2016)

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

Abstract: Post-translational histone modifications and linker histone incorporation regulate chromatin structure and genome activity. How these systems interface on a molecular level is unclear. Using biochemistry and NMR spectroscopy, we deduced mechanistic insights into the modification behavior of N-terminal histone H3 tails in different nucleosomal contexts. We find that linker histones generally inhibit modifications of different H3 sites and reduce H3 tail dynamics in nucleosomes. These effects are caused by modulations of electrostatic interactions of H3 tails with linker DNA and largely depend on the C-terminal domains of linker histones. In agreement, linker histone occupancy and H3 tail modifications segregate on a genome-wide level. Charge-modulating modifications such as phosphorylation and acetylation weaken transient H3 tail-linker DNA interactions, increase H3 tail dynamics, and, concomitantly, enhance general modifiability. We propose that alterations of H3 tail-linker DNA interactions by linker histones and charge-modulating modifications execute basal control mechanisms of chromatin function.

Lipopeptide-based micellar and liposomal carriers: Influence of surface charge and particle size on cellular uptake into blood brain barrier cells
Sydow, K., Nikolenko, H., Lorenz, D., Müller(*), R. H.; Dathe, M.
Eur J Pharm Biopharm, 109:130-139
(2016)

Tags: Peptide-Lipid-Interaction/ Peptide Transport (Dathe)

Abstract: Lipopeptide-based micelles and liposomes were found to differ in cell recognition and uptake mode into blood brain barrier (BBB) endothelial cells. Here we analyse the role of size and surface charge of micelles and liposomes composed of different lipopeptide sequences with respect to uptake into human brain capillary (HBMEC) and aortic (HAoEC) endothelial cells. Comparable to the dipalmitoylated apolipoprotein E-derived P2A2, lipopeptides of cationic poly-arginine (P2Rn), poly-lysine (P2Kn) and an anionic glutamic-acid sequence (P2En) self assemble into micelles (12-14nm in diameter) with high surface charge density, and bind to small (SUVs, about 24nm in diameter) and large (LUV, about 100nm in diameter) liposomes at variable lipid to peptide ratios. The interaction pattern of the resulting particles with endothelial cells is highly variable as revealed by confocal laser scanning microscopic (CLSM) and fluorescence assisted cell sorting (FACS) studies. Micelles and SUVs with high P2A2 density are efficiently and selectively internalized into HBMEC. P2Kn micelles strongly accumulate in both the cytosol and at the cell membrane, while the interaction of liposomes tagged with a low amount of P2A2 and P2Kn with the cells was reduced. Anionic micelles seem to dissociate in the presence of cells and P2En molecules incorporate into the cellular membrane whereas the negatively charged liposomes hardly interact with cells. Surprisingly, all poly-R-based particles show high selectivity for HBMEC compared to HAoEC, independent of particle size and peptide surface density. The P2Rn-mediated internalization is highly efficient and partially clathrin-dependent. The oligo-R lipopeptide is considered to be most promising to selectively transport different drug carriers into the blood brain barrier.

Structural disorder of monomeric alpha-synuclein persists in mammalian cells
Theillet, F. X., Binolfi, A., Bekei, B., Martorana(*), A., Rose, H. M., Stuiver, M., Verzini, S., Lorenz, D., van Rossum, M., Goldfarb(*), D.; Selenko, P.
Nature, 530:45-50
(2016)

Tags: In-Cell NMR (Selenko), Cellular Imaging (Wiesner)

Abstract: Intracellular aggregation of the human amyloid protein alpha-synuclein is causally linked to Parkinson's disease. While the isolated protein is intrinsically disordered, its native structure in mammalian cells is not known. Here we use nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectroscopy to derive atomic-resolution insights into the structure and dynamics of alpha-synuclein in different mammalian cell types. We show that the disordered nature of monomeric alpha-synuclein is stably preserved in non-neuronal and neuronal cells. Under physiological cell conditions, alpha-synuclein is amino-terminally acetylated and adopts conformations that are more compact than when in buffer, with residues of the aggregation-prone non-amyloid-beta component (NAC) region shielded from exposure to the cytoplasm, which presumably counteracts spontaneous aggregation. These results establish that different types of crowded intracellular environments do not inherently promote alpha-synuclein oligomerization and, more generally, that intrinsic structural disorder is sustainable in mammalian cells.

Young, active and well-connected: adult-born neurons in the zebra finch are activated during singing
Tokarev(*), K., Boender(*), A. J., Classen, G. A.; Scharff(*), C.
Brain Struct Funct, 221:1833-1843
(2016)

Tags: Molecular Pharmacology and Cell Biology (Haucke)

Abstract: Neuronal replacement in the pallial song control nucleus HVC of adult zebra finches constitutes an interesting case of homeostatic plasticity; in spite of continuous addition and attrition of neurons in ensembles that code song elements, adult song remains remarkably invariant. New neurons migrate into HVC and later synapse with their target, arcopallial song nucleus RA (HVCRA). New HVCRA neurons respond to auditory stimuli (in anaesthetised animals), but whether and when they become functionally active during singing is unknown. We studied this, using 5-bromo-2'-deoxyuridine to birth-date neurons, combined with immunohistochemical detection of immediate-early gene (IEG) expression and retrograde tracer injections into RA to track connectivity. Interestingly, singing was followed by IEG expression in a substantial fraction of new neurons that were not retrogradely labelled from RA, suggesting a possible role in HVC-intrinsic network function. As new HVC neurons matured, the proportion of HVCRA neurons that expressed IEGs after singing increased significantly. Since it was previously shown that singing induces IEG expression in HVC also in deaf birds and that hearing song does not induce IEG expression in HVC, our data provide the first direct evidence that new HVC neurons are engaged in song motor behaviour.

Inactivation and Anion Selectivity of Volume-regulated Anion Channels (VRACs) Depend on C-terminal Residues of the First Extracellular Loop
Ullrich, F., Reincke, S. M., Voss, F. K., Stauber, T.; Jentsch, T. J.
J Biol Chem, 291:17040-17048
(2016)

Tags: Physiology and Pathology of Ion Transport (Jentsch)

Abstract: Canonical volume-regulated anion channels (VRACs) are crucial for cell volume regulation and have many other important roles, including tumor drug resistance and release of neurotransmitters. Although VRAC-mediated swelling-activated chloride currents (ICl,vol) have been studied for decades, exploration of the structure-function relationship of VRAC has become possible only after the recent discovery that VRACs are formed by differently composed heteromers of LRRC8 proteins. Inactivation of ICl,vol at positive potentials, a typical hallmark of VRACs, strongly varies between native cell types. Exploiting the large differences in inactivation between different LRRC8 heteromers, we now used chimeras assembled from isoforms LRRC8C and LRRC8E to uncover a highly conserved extracellular region preceding the second LRRC8 transmembrane domain as a major determinant of ICl,vol inactivation. Point mutations identified two amino acids (Lys-98 and Asp-100 in LRRC8A and equivalent residues in LRRC8C and -E), which upon charge reversal strongly altered the kinetics and voltage dependence of inactivation. Importantly, charge reversal at the first position also reduced the iodide > chloride permeability of ICl,vol This change in selectivity was stronger when both the obligatory LRRC8A subunit and the other co-expressed isoform (LRR8C or -E) carried such mutations. Hence, the C-terminal part of the first extracellular loop not only determines VRAC inactivation but might also participate in forming its outer pore. Inactivation of VRACs may involve a closure of the extracellular mouth of the permeation pathway.

Inositol polyphosphates intersect with signaling and metabolic networks via two distinct mechanisms
Wu(*), M., Chong, L. S., Perlman(*), D. H., Resnick(*), A. C.; Fiedler, D.
Proc Natl Acad Sci U S A, 113:E6757-E6765
(2016)

Tags: Chemical Biology I (Fiedler)

Abstract: Inositol-based signaling molecules are central eukaryotic messengers and include the highly phosphorylated, diffusible inositol polyphosphates (InsPs) and inositol pyrophosphates (PP-InsPs). Despite the essential cellular regulatory functions of InsPs and PP-InsPs (including telomere maintenance, phosphate sensing, cell migration, and insulin secretion), the majority of their protein targets remain unknown. Here, the development of InsP and PP-InsP affinity reagents is described to comprehensively annotate the interactome of these messenger molecules. By using the reagents as bait, >150 putative protein targets were discovered from a eukaryotic cell lysate (Saccharomyces cerevisiae). Gene Ontology analysis of the binding partners revealed a significant overrepresentation of proteins involved in nucleotide metabolism, glucose metabolism, ribosome biogenesis, and phosphorylation-based signal transduction pathways. Notably, we isolated and characterized additional substrates of protein pyrophosphorylation, a unique posttranslational modification mediated by the PP-InsPs. Our findings not only demonstrate that the PP-InsPs provide a central line of communication between signaling and metabolic networks, but also highlight the unusual ability of these molecules to access two distinct modes of action.

A Stable Pyrophosphoserine Analog for Incorporation into Peptides and Proteins
Yates(*), L. M.; Fiedler, D.
ACS Chem Biol, 11:1066-1073
(2016)

Tags: Chemical Biology I (Fiedler)

Abstract: Protein pyrophosphorylation is a covalent modification of proteins, mediated by the inositol pyrophosphate messengers. Although the inositol pyrophosphates have been linked to a range of cellular processes, the role of protein pyrophosphorylation remains minimally characterized in vivo. The inherent instability of the phosphoanhydride bond has hampered the development of useful bioanalytical techniques to interrogate this novel signaling mechanism. Here, we describe the preparation of a pyrophosphoserine analog containing a stable methylene-bisphosphonate group that is compatible with solid-phase peptide synthesis. The resulting peptides demonstrate enhanced stability in Eukaryotic cell lysates and mammalian plasma and display resistance toward chemical degradation, when compared to the corresponding pyrophosphopeptides. In addition, the peptides containing the stable pyrophosphoserine analog are highly compatible with common ligation methods, such as native chemical ligation, maleimide conjugation, and glutaraldehyde ligation. The bisphosphonate-containing peptides will, therefore, be well-suited for future pyrophosphoserine antibody generation and affinity capture of pyrophosphoprotein binding partners and provide a key entry point to study the regulatory role of protein pyrophosphorylation.

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

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