Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Germany  (13)
  • 1
    Keywords: APOPTOSIS ; CANCER ; CELLS ; EXPRESSION ; CELL ; Germany ; IN-VIVO ; VIVO ; PROTEIN ; cell line ; DIFFERENTIATION ; DNA ; DOMAIN ; image analysis ; FLOW ; cell cycle ; CELL-CYCLE ; CYCLE ; SPECTROSCOPY ; IDENTIFICATION ; PROGRESSION ; CHROMATIN ; INDUCED APOPTOSIS ; CYCLE PROGRESSION ; CELL-LINE ; LINE ; acetylation ; REGION ; REGIONS ; MAMMALIAN-CELLS ; LENGTH ; REORGANIZATION ; STRUCTURAL-CHANGES ; HISTONE DEACETYLASE ; FLOW-CYTOMETRY ; INTERPHASE ; CHROMATIN STRUCTURE ; S-PHASE ; DOMAINS ; TRICHOSTATIN-A ; CORRELATION SPECTROSCOPY ; ARREST ; ACETYLTRANSFERASE ; SCALE ; DEPENDENCE ; fractal dimension ; DEACETYLASE INHIBITORS ; GENE-CONTROL ; HYPERACETYLATION ; image correlation ; NUCLEOSOME CORE ; TSA
    Abstract: The effect of trichostatin A (TSA)-induced histone acetylation on the interphase chromatin structure was visualized in vivo with a HeLa cell line stably expressing histone H2A, which was fused to enhanced yellow fluorescent protein. The globally increased histone acetylation caused a reversible decondensation of dense chromatin regions and led to a more homogeneous distribution. These structural changes were quantified by image correlation spectroscopy and by spatially resolved scaling analysis. The image analysis revealed that a chromatin reorganization on a length scale from 200 nm to 〉1 mum was induced consistent with the opening of condensed chromatin domains containing several Mb of DNA. The observed conformation changes could be assigned to the folding of chromatin during G1 phase by characterizing the effect of TSA on cell cycle progression and developing a protocol that allowed the identification of G1 phase cells on microscope coverslips. An analysis by flow cytometry showed that the addition of TSA led to a significant arrest of cells in S phase and induced apoptosis. The concentration dependence of both processes was studied
    Type of Publication: Journal article published
    PubMed ID: 15292402
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    Keywords: RECEPTOR ; CELL ; Germany ; SUPPORT ; SITE ; PROTEIN ; PROTEINS ; ACTIVATION ; BINDING ; BIOLOGY ; MOLECULAR-BIOLOGY ; TRANSPORT ; MEMBRANE ; CRYSTAL-STRUCTURE ; RECEPTORS ; molecular biology ; molecular ; TECHNOLOGY ; ENVELOPE ; USA ; PROTEIN IMPORT ; BINDING PROTEINS ; FUNCTIONAL-ANALYSIS ; interactions ; NUCLEOTIDE ; ACTIVATING PROTEINS ; MACROMOLECULAR STRUCTURES ; OUTER ENVELOPE MEMBRANE ; PREPROTEIN RECEPTOR ; SIGNAL RECOGNITION PARTICLE ; TOC-GTPASES
    Abstract: Transport of precursor proteins across chloroplast membranes involves the GTPases Toc33/34 and Toc159 at the outer chloroplast envelope. The small GTPase Toc33/34 can homodimerize, but the regulation of this interaction has remained elusive. We show that dimerization is independent of nucleotide loading state, based on crystal structures of dimeric Pisum sativum Toc34 and monomeric Arabidopsis thaliana Toc33. An arginine residue is-in the dimer-positioned to resemble a GAP arginine finger. However, GTPase activation by dimerization is sparse and active site features do not explain catalysis, suggesting that the homodimer requires an additional factor as coGAP. Access to the catalytic center and an unusual switch I movement in the dimeric structure support this finding. Potential binding sites for interactions within the Toc translocon or with precursor proteins can be derived from the structures
    Type of Publication: Journal article published
    PubMed ID: 18400179
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    Keywords: RECEPTOR ; Germany ; MODEL ; MODELS ; PROTEIN ; COMPONENTS ; ACTIVATION ; COMPLEX ; MECHANISM ; IMPACT ; DOMAIN ; BINDING ; BIOLOGY ; MOLECULAR-BIOLOGY ; VARIANTS ; ACID ; MEMBRANE ; CRYSTAL-STRUCTURE ; EXCHANGE ; TRANSLOCATION ; INSIGHTS ; DOMAINS ; molecular biology ; molecular ; VARIANT ; SWITCH ; USA ; BINDING PROTEINS ; X-RAY ; NUCLEOTIDE ; alanine ; ALUMINUM FLUORIDE ; CHLOROPLAST PROTEIN IMPORT ; OUTER ENVELOPE ; TRANSLOCON
    Abstract: Precursor protein translocation across the outer chloroplast membrane depends on the action of the Toc complex, containing GTPases as recognizing receptor components. The G domains of the GTPases are known to dimerize. In the dimeric conformation an arginine contacts the phosphate moieties of bound nucleotide in trans. Kinetic studies suggested that the arginine in itself does not act as an arginine finger of a reciprocal GTPase-activating protein (GAP). Here we investigate the specific function of the residue in two GTPase homologues. Arginine to alanine replacement variants have significantly reduced affinities for dimerization compared with wild-type GTPases. The amino acid exchange does not impact on the overall fold and nucleotide binding, as seen in the monomeric x-ray crystallographic structure of the Arabidopsis Toc33 arginine-alanine replacement variant at 2.0 A. We probed the catalytic center with the transition state analogue GDP/AlFx using NMR and analytical ultracentrifugation. AlFx binding depends on the arginine, suggesting the residue can play a role in catalysis despite the non-GAP nature of the homodimer. Two non-exclusive functional models are discussed: 1) the coGAP hypothesis, in which an additional factor activates the GTPase in homodimeric form; and 2) the switch hypothesis, in which a protein, presumably the large Toc159 GTPase, exchanges with one of the homodimeric subunits, leading to activation
    Type of Publication: Journal article published
    PubMed ID: 18541539
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    Keywords: ENERGIES ; EXPRESSION ; Germany ; GENE ; GENE-EXPRESSION ; PROTEIN ; PROTEINS ; DNA ; IMPACT ; SIMULATION ; BINDING ; CHROMATIN ; gene expression ; ENERGY ; EXCHANGE ; ANGSTROM RESOLUTION ; MONTE-CARLO ; ORDER ; CHAIN ; higher-order structure ; LINKER HISTONE ; nucleosomes ; PROTOCOL ; interaction ; NUCLEOSOME ; MONTE-CARLO-SIMULATION ; USA ; CHROMATIN FIBER ; COMPUTER-SIMULATION ; SCANNING FORCE MICROSCOPY ; computer simulations ; CORE PARTICLE ; SHAPE ; COOPERATIVE BINDING ; NUCLEOSOME REPEAT LENGTH
    Abstract: The folding of the nucleosome chain into a chromatin fiber modulates DNA accessibility and is therefore an important factor for the control of gene expression. The fiber conformation depends crucially on the interaction between individual nucleosomes. However, this parameter has not been accurately determined experimentally, and it is affected by posttranslational histone modi. cations and binding of chromosomal proteins. Here, the effect of different internucleosomal interaction strengths on the fiber conformation was investigated by Monte Carlo computer simulations. The fiber geometry was modeled to fit that of chicken erythrocyte chromatin, which has been examined in numerous experimental studies. In the Monte Carlo simulation, the nucleosome shape was described as an oblate spherocylinder, and a replica exchange protocol was developed to reach thermal equilibrium for a broad range of internucleosomal interaction energies. The simulations revealed the large impact of the nucleosome geometry and the nucleosome repeat length on the compaction of the chromatin fiber. At high internucleosomal interaction energies, a lateral self-association of distant fiber parts and an interdigitation of nucleosomes were apparent. These results identify key factors for the control of the compaction and higher order folding of the chromatin fiber
    Type of Publication: Journal article published
    PubMed ID: 18658212
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    Keywords: IN-VITRO ; tumor ; Germany ; MICROSCOPY ; MODEL ; PROTEIN ; PROTEINS ; transcription ; DNA ; cell cycle ; CELL-CYCLE ; CYCLE ; PATTERNS ; DNA-DAMAGE ; DNA-REPLICATION ; ORGANIZATION ; PML ; RAR-ALPHA ; PATTERN ; telomere ; covalent modification ; 4PI MICROSCOPY ; CELL BIOLOGY ; SUMOYLATION ; PROTEIN STRUCTURES ; BODY FORMATION ; CHROMATIN ACCESSIBILITY ; Promyelocytic leukemia nuclear bodies ; SUMO MODIFICATION
    Abstract: Promyelocytic leukemia nuclear bodies (PML-NBs) are mobile subnuclear organelles formed by PML and Sp100 protein. They have been reported to have a role in transcription, DNA replication and repair, telomere lengthening, cell cycle control and tumor suppression. We have conducted high-resolution 4Pi fluorescence laser-scanning microscopy studies complemented with correlative electron microscopy and investigations of the accessibility of the PML-NB subcompartment. During interphase PML-NBs adopt a spherical organization characterized by the assembly of PML and Sp100 proteins into patches within a 50- to 100-nm-thick shell. This spherical shell of PML and Sp100 imposes little constraint to the exchange of components between the PML-NB interior and the nucleoplasm. Post-translational SUMO modifications, telomere repeats and heterochromatin protein 1 were found to localize in characteristic patterns with respect to PML and Sp100. From our findings, we derived a model that explains how the three-dimensional organization of PML-NBs serves to concentrate different biological activities while allowing for an efficient exchange of components
    Type of Publication: Journal article published
    PubMed ID: 20130140
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    facet.materialart.
    Unknown
    Molecular Systems Biology 2 (), Art. Nr.: 44- 
    Keywords: CELL ; Germany ; imaging ; INFORMATION ; GENE-EXPRESSION ; GENOME ; RNA ; DIFFERENTIATION ; MESSENGER-RNA ; FLOW ; DISCOVERY ; LIVING CELLS ; REGULATOR ; RE ; RNA INTERFERENCE ; ROLES ; function ; HUMAN-CELLS ; COMPLEX ORGANISMS ; DNA FRAGMENTS ; MULTIPLEX AMPLIFICATION ; non-coding RNA ; NONCODING RNAS ; PADLOCK PROBES ; regulatory RNA networks ; RNA visualization ; SMALL RNAS
    Abstract: The past few years have brought about a fundamental change in our understanding and definition of the RNA world and its role in the functional and regulatory architecture of the cell. The discovery of small RNAs that regulate many aspects of differentiation and development have joined the already known non-coding RNAs that are involved in chromosome dosage compensation, imprinting, and other functions to become key players in regulating the flow of genetic information. It is also evident that there are tens or even hundreds of thousands of other non-coding RNAs that are transcribed from the mammalian genome, as well as many other yet-to-be-discovered small regulatory RNAs. In the recent symposium RNA: Networks & Imaging held in Heidelberg, the dual roles of RNA as a messenger and a regulator in the flow of genetic information were discussed and new molecular genetic and imaging methods to study RNA presented
    Type of Publication: Journal article published
    PubMed ID: 16924265
    Signatur Availability
    BibTip Others were also interested in ...
  • 7
    Keywords: EXPRESSION ; Germany ; DISTINCT ; PROTEIN ; SACCHAROMYCES-CEREVISIAE ; COMPLEX ; COMPLEXES ; DNA ; BINDING ; SEQUENCE ; SEQUENCES ; LINKAGE ; ELEMENT ; PATTERNS ; CHROMATIN ; Drosophila ; PROMOTER ; REGION ; PRODUCT ; REGIONS ; TRANSLOCATION ; CHROMATIN STRUCTURE ; REGULATOR ; AFFINITY ; TRANSCRIPTIONAL REGULATION ; DNA-SEQUENCE ; FEATURES ; PATTERN ; END ; GENE-TRANSCRIPTION ; ISWI ; USA ; nucleosome positioning ; comparison ; ACCESSIBILITY ; HISTONE OCTAMER ; nucleosome remodeling ; ACF ; SWI-SNF ; YEAST ALPHA-2 REPRESSOR
    Abstract: Chromatin-remodeling complexes can translocate nucleosomes along the DNA in an ATP-coupled reaction. This process is an important regulator of all DNA-dependent processes because it determines whether certain DNA sequences are found in regions between nucleosomes with increased accessibility for other factors or wrapped around the histone octamer complex. In a comparison of seven different chromatin-remodeling machines (ACF, ISWI, Snf2H, Chd1, Mi-2, Brg1, and NURF), it is demonstrated that these complexes can read out DNA sequence features to establish specific nucleosome-positioning patterns. For one of the remodelers, ACF, we identified a 40-bp DNA sequence element that directs nucleosome positioning. Furthermore, we show that nucleosome positioning by the remodelers ACF and Chd1 is determined by a reduced affinity to the end product of the translocation reaction. The results suggest that the linkage of differential remodeling activities with the intrinsic binding preferences of nucleosomes can result in establishing distinct chromatin structures that depend on the DNA sequence and define the DNA accessibility for other protein factors
    Type of Publication: Journal article published
    PubMed ID: 17893337
    Signatur Availability
    BibTip Others were also interested in ...
  • 8
    Keywords: ENVIRONMENT ; CELL ; Germany ; MODEL ; DISTINCT ; GENE-EXPRESSION ; GENOME ; PROTEINS ; COMPONENTS ; mechanisms ; BIOLOGY ; FORM ; CHROMATIN ; genetics ; COMPONENT ; NUCLEUS ; DNA-REPLICATION ; CHROMOSOME TERRITORIES ; ORGANIZATION ; heredity ; LAYER ; BODIES ; review ; assembly ; interaction ; PRINCIPLES ; NUCLEAR ; BIOLOGICAL-ACTIVITY ; function ; OCCURS ; modification ; MITOTIC CHROMOSOMES
    Abstract: The dynamic organization of the cell nucleus into subcompartments with distinct biological activities represents an important regulatory layer for cell function. Recent studies provide new insights into the principles, by which nuclear organelles form. This process frequently occurs in a self-organizing manner leading to the assembly of stable but plastic structures from multiple relatively weak interaction forces. These can rearrange into different functional states in response to specific modifications of the constituting components or changes in the nuclear environment
    Type of Publication: Journal article published
    PubMed ID: 17913491
    Signatur Availability
    BibTip Others were also interested in ...
  • 9
    Keywords: ENERGIES ; CELL ; Germany ; MICROSCOPY ; imaging ; VISUALIZATION ; PROTEIN ; SAMPLE ; SAMPLES ; COMPLEX ; COMPLEXES ; DNA ; AIR ; BINDING ; SEQUENCE ; DIFFERENCE ; ENERGY ; XENOPUS ; MICA ; QUANTITATIVE-ANALYSIS ; ANGSTROM RESOLUTION ; CHROMATIN FIBER STRUCTURE ; COMPACTION ; CRYOELECTRON MICROSCOPY ; NONRANDOM BEHAVIOR ; NUCLEOSOME CORE PARTICLE
    Abstract: The conformation of mononucleosome complexes reconstituted with recombinant core histones on a 614-basepair-long DNA fragment containing the Xenopus borealis 5S rRNA nucleosome positioning sequence was studied by scanning/atomic force microscopy in the absence or presence of linker histone H1. Imaging without prior fixation was conducted with air-dried samples and with mononucleosomes that were injected directly into the scanning force microscopy fluid cell and visualized in buffer. From a quantitative analysis of similar to 1,700 complexes, the following results were obtained: i), In the absence of H1, a preferred location of the nucleosome at the X. borealis 5S rRNA sequence in the center of the DNA was detected. From the distribution of nucleosome positions, an energy difference of binding to the 5S rRNA sequence of DeltaDeltaG approximate to 3 kcal mol(-1) as compared to a random sequence was estimated. Upon addition of H1, a significantly reduced preference of nucleosome binding to this sequence was observed. ii), The measured entry-exit angles of the DNA at the nucleosome in the absence of H1 showed two maxima at 81 +/- 29degrees and 136 +/- 18degrees (air-dried samples), and 78 +/- 25degrees and 137 +/- 25degrees (samples imaged in buffer solution). In the presence of H1, the species with the smaller entry-exit angle was stabilized, yielding average values of 88 6 348 for complexes in air and 85 +/- 10degrees in buffer solution. iii), The apparent contour length of the nucleosome complexes was shortened by 34 +/- 13 nm as compared to the free DNA due to wrapping of the DNA around the histone octamer complex. Considering an 11 nm diameter of the nucleosome core complex, this corresponds to a total of 145 +/- 34 basepairs that are wound around the nucleosome
    Type of Publication: Journal article published
    PubMed ID: 14645090
    Signatur Availability
    BibTip Others were also interested in ...
  • 10
    Keywords: CELLS ; CELL ; Germany ; IN-VIVO ; MICROSCOPY ; VIVO ; imaging ; INFORMATION ; SYSTEM ; SYSTEMS ; COMPLEX ; BIOLOGY ; MOLECULAR-BIOLOGY ; SIGNAL ; FIELD ; genetics ; LOCALIZATION ; NETHERLANDS ; FLUORESCENCE ; heredity ; ARCHITECTURE ; molecular biology ; molecular ; RE ; FLUORESCENCE MICROSCOPY ; analysis ; NUCLEAR ; 3D ; SIGNATURE ; 2 OBJECTIVE LENSES ; 3D WIDEFIELD MICROSCOPY ; AXIAL RESOLUTION ; TEMPERATURE ; EXCITATION ; ERRORS ; three-dimensional ; live cell imaging ; SECONDS ; STORM ; DATA-ACQUISITION ; 3-DIMENSIONAL SUPERRESOLUTION ; DISTANCE MEASUREMENTS ; FPALM ; localization microscopy ; nanosizing ; NANOSTRUCTURE ; OPTICAL RECONSTRUCTION MICROSCOPY ; PALM ; PALMIRA ; SALM ; SIZE DETERMINATION ; SMI microscopy ; SPDM ; Vertico-SMI microscope
    Abstract: Spatially modulated illumination (SMI) microscopy is a method of wide field fluorescence microscopy featuring interferometric illumination, which delivers structural information about nanoscale architecture in fluorescently labelled cells. The first prototype of the SMI microscope proved its applicability to a wide range of biological questions. For the SMI live cell imaging this system was enhanced in terms of the development of a completely new upright configuration. This so called Vertico-SMI transfers the advantages of SMI nanoscaling to vital biological systems, and is shown to work consistently at different temperatures using both oil- and water-immersion objective lenses. Furthermore, we increased the speed of data acquisition to minimize errors in the detection signal resulting from cellular or object movement. By performing accurate characterization, the present Vertico-SMI now offers a fully-fledged microscope enabling a complete three-dimensional (3D) SMI data stack to be acquired in less than 2 seconds. We have performed live cell measurements of a tet-operator repeat insert in U2OS cells, which provided the first in vivo signatures of subnuclear complexes. Furthermore, we have successfully implemented an optional optical configuration allowing the generation of high-resolution localization microscopy images of a nuclear pore complex distribution
    Type of Publication: Journal article published
    PubMed ID: 18461478
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...