Margot P Scheffer

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The shear-responsive transcription factor Krüppel-like factor 2 (KLF2) is a critical regulator of endothelial gene expression patterns induced by atheroprotective flow. As microRNAs (miRNAs) post-transcriptionally control gene expression in many pathogenic and physiological processes, we investigated the regulation of miRNAs by KLF2 in endothelial cells.(More)
Correlative microscopy incorporates the specificity of fluorescent protein labeling into high-resolution electron micrographs. Several approaches exist for correlative microscopy, most of which have used the green fluorescent protein (GFP) as the label for light microscopy. Here we use chemical tagging and synthetic fluorophores instead, in order to achieve(More)
Chromatin folding in eukaryotes fits the genome into the limited volume of the cell nucleus. Formation of higher-order chromatin structures attenuates DNA accessibility, thus contributing to the control of essential genome functions such as transcription, DNA replication, and repair. The 30-nm fiber is thought to be the first hierarchical level of chromatin(More)
The robust alignment of tilt-series collected for cryo-electron tomography in the absence of fiducial markers, is a problem that, especially for tilt-series of vitreous sections, still represents a significant challenge. Here we present a complete software package that implements a cross-correlation-based procedure that tracks similar image features that(More)
The helical filaments of the cyanide hydratase from Gloeocercospora sorghi have been reconstructed in three dimensions from freeze dried, unidirectionally shadowed specimens using iterative real-space helical reconstruction. The average power spectrum of all selected images has three clear reflections on different layer lines. The reconstruction is(More)
Yeast prions constitute a "protein-only" mechanism of inheritance that is widely deployed by wild yeast to create diverse phenotypes. One of the best-characterized prions, [PSI(+)], is governed by a conformational change in the prion domain of Sup35, a translation-termination factor. When this domain switches from its normal soluble form to an insoluble(More)
In this study, electron tomograms of plunge-frozen isolated chromatin in both open and compacted form were recorded. We have resolved individual nucleosomes in these tomograms in order to provide a 3D view of the arrangement of nucleosomes within chromatin fibers at different compaction states. With an optimized template matching procedure we obtained(More)
The centromeric histone H3 variant centromeric protein A (CENP-A), whose sequence is the least conserved among all histone variants, is responsible for specifying the location of the centromere. Here, we present a comprehensive study of CENP-A nucleosome arrays by cryo-electron tomography. We see that CENP-A arrays have different biophysical properties than(More)
RNA polymerase I (Pol I) is a highly processive enzyme that transcribes ribosomal DNA (rDNA) and regulates growth of eukaryotic cells. Crystal structures of free Pol I from the yeast Saccharomyces cerevisiae have revealed dimers of the enzyme stabilized by a 'connector' element and an expanded cleft containing the active centre in an inactive conformation.(More)
Mycoplasma genitalium, the causative agent of non-gonococcal urethritis and pelvic inflammatory disease in humans, is a small eubacterium that lacks a peptidoglycan cell wall. On the surface of its plasma membrane is the major surface adhesion complex, known as NAP that is essential for adhesion and gliding motility of the organism. Here, we have performed(More)
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