Biology subjects

Sauer, M.

Publications and source records attributed to Sauer, M..

3 recordsLinked to original sources

bioRxiv2018

Imaging beyond the super-resolution limits using ultrastructure expansion microscopy (UltraExM)

For decades, electron microscopy (EM) was the only method able to reveal the ultrastructure of cellular organelles and molecular complexes because of the diffraction limit of optical microscopy. In recent past, the emergence of superresolution fluorescence microscopy enabled the visualization of cellular structures with so far unmatched spatial resolution approaching virtually molecular dimensions. Despite these technological advances, currently super-resolution microscopy does not permit the same resolution level as provided by electron microscopy, impeding the attribution of a protein to an ultrastructural element. Here, we report a novel method of near-native expansion microscopy (UltraExM), enabling the visualization of preserved ultrastructures of macromolecular assemblies with subdiffraction-resolution by standard optical microscopy. UltraExM revealed for the first time the ultrastructural localization of tubulin glutamylation in centrioles. Combined with super-resolution microscopy, UltraExM unveiled the centriolar chirality, an ultrastructural signature, which was only visualizable by electron microscopy.

cell biology↗

bioRxiv2017

DHX36 binding at G-rich sites in mRNA untranslated regions promotes translation

Translation efficiency can be affected by mRNA stability and secondary structures, including so-called G-quadruplex (G4) structures. The highly conserved and essential DEAH-box helicase DHX36/RHAU is able to resolve G4 structures on DNA and RNA in vitro, however a system-wide analysis of DHX36 targets and function is lacking. We globally mapped DHX36 occupancy in human cell lines and found that it preferentially binds to G-rich sequences in the coding sequences (CDS) and 5' and 3' untranslated regions (UTR) of more than 4,500 mRNAs. Functional analyses, including RNA sequencing, ribosome footprinting, and quantitative mass spectrometry revealed that DHX36 decreased target mRNA stability. However, target mRNA accumulation in DHX36 KO cells did not lead to a significant increase in ribosome footprints or protein output indicating that they were translationally incompetent. We hypothesize that DHX36 resolves G4 and other structures that interfere with efficient translation initiation.

bioinformatics↗

bioRxiv2017

Boosting The Localization Precision Of dSTORM By Biocompatible Metal-Dielectric Coated Glass Coverslips

Super-resolution techniques such as direct Stochastic Optical Reconstruction Microscopy (dSTORM) have become versatile and well-established tools for biological imaging over the last century. Here, we theoretically and experimentally show that clever combination of different fluorescence modalities allows further improvements. We found that the interaction of fluorophores with plasmonic surfaces boost super-resolution performance in dSTORM approaches as it allows for tailoring the excitation and emission properties. The strength of the approach is that no further specialized microscope setup is required as the described enhancement solely rely on metal-dielectric coated glass coverslips that are straightforward to fabricate. Such biocompatible plasmonic nanolayers enhance the signal-to-noise ratio of dSTORM, and thus sharpens the localization precision by a factor of two.

biophysics↗