@article{BalakrishnanHemmenChoudhuryetal.2022, author = {Balakrishnan, Ashwin and Hemmen, Katherina and Choudhury, Susobhan and Krohn, Jan-Hagen and Jansen, Kerstin and Friedrich, Mike and Beliu, Gerti and Sauer, Markus and Lohse, Martin J. and Heinze, Katrin G.}, title = {Unraveling the hidden temporal range of fast β2-adrenergic receptor mobility by time-resolved fluorescence}, series = {Communications Biology}, volume = {5}, journal = {Communications Biology}, number = {1}, doi = {10.1038/s42003-022-03106-4}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-301140}, year = {2022}, abstract = {G-protein-coupled receptors (GPCRs) are hypothesized to possess molecular mobility over a wide temporal range. Until now the temporal range has not been fully accessible due to the crucially limited temporal range of available methods. This in turn, may lead relevant dynamic constants to remain masked. Here, we expand this dynamic range by combining fluorescent techniques using a spot confocal setup. We decipher mobility constants of β\(_{2}\)-adrenergic receptor over a wide time range (nanosecond to second). Particularly, a translational mobility (10 µm\(^{2}\)/s), one order of magnitude faster than membrane associated lateral mobility that explains membrane protein turnover and suggests a wider picture of the GPCR availability on the plasma membrane. And a so far elusive rotational mobility (1-200 µs) which depicts a previously overlooked dynamic component that, despite all complexity, behaves largely as predicted by the Saffman-Delbr{\"u}ck model.}, language = {en} } @article{EiringMcLaughlinMatikondaetal.2021, author = {Eiring, Patrick and McLaughlin, Ryan and Matikonda, Siddharth S. and Han, Zhongying and Grabenhorst, Lennart and Helmerich, Dominic A. and Meub, Mara and Beliu, Gerti and Luciano, Michael and Bandi, Venu and Zijlstra, Niels and Shi, Zhen-Dan and Tarasov, Sergey G. and Swenson, Rolf and Tinnefeld, Philip and Glembockyte, Viktorija and Cordes, Thorben and Sauer, Markus and Schnermann, Martin J.}, title = {Targetable conformationally restricted cyanines enable photon-count-limited applications}, series = {Angewandte Chemie Internationale Edition}, volume = {60}, journal = {Angewandte Chemie Internationale Edition}, number = {51}, doi = {10.1002/anie.202109749}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256559}, pages = {26685-26693}, year = {2021}, abstract = {Cyanine dyes are exceptionally useful probes for a range of fluorescence-based applications, but their photon output can be limited by trans-to-cis photoisomerization. We recently demonstrated that appending a ring system to the pentamethine cyanine ring system improves the quantum yield and extends the fluorescence lifetime. Here, we report an optimized synthesis of persulfonated variants that enable efficient labeling of nucleic acids and proteins. We demonstrate that a bifunctional sulfonated tertiary amide significantly improves the optical properties of the resulting bioconjugates. These new conformationally restricted cyanines are compared to the parent cyanine derivatives in a range of contexts. These include their use in the plasmonic hotspot of a DNA-nanoantenna, in single-molecule F{\"o}rster-resonance energy transfer (FRET) applications, far-red fluorescence-lifetime imaging microscopy (FLIM), and single-molecule localization microscopy (SMLM). These efforts define contexts in which eliminating cyanine isomerization provides meaningful benefits to imaging performance.}, language = {en} } @article{KuhlemannBeliuJanzenetal.2021, author = {Kuhlemann, Alexander and Beliu, Gerti and Janzen, Dieter and Petrini, Enrica Maria and Taban, Danush and Helmerich, Dominic A. and Doose, S{\"o}ren and Bruno, Martina and Barberis, Andrea and Villmann, Carmen and Sauer, Markus and Werner, Christian}, title = {Genetic Code Expansion and Click-Chemistry Labeling to Visualize GABA-A Receptors by Super-Resolution Microscopy}, series = {Frontiers in Synaptic Neuroscience}, volume = {13}, journal = {Frontiers in Synaptic Neuroscience}, issn = {1663-3563}, doi = {10.3389/fnsyn.2021.727406}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-251035}, year = {2021}, abstract = {Fluorescence labeling of difficult to access protein sites, e.g., in confined compartments, requires small fluorescent labels that can be covalently tethered at well-defined positions with high efficiency. Here, we report site-specific labeling of the extracellular domain of γ-aminobutyric acid type A (GABA-A) receptor subunits by genetic code expansion (GCE) with unnatural amino acids (ncAA) combined with bioorthogonal click-chemistry labeling with tetrazine dyes in HEK-293-T cells and primary cultured neurons. After optimization of GABA-A receptor expression and labeling efficiency, most effective variants were selected for super-resolution microscopy and functionality testing by whole-cell patch clamp. Our results show that GCE with ncAA and bioorthogonal click labeling with small tetrazine dyes represents a versatile method for highly efficient site-specific fluorescence labeling of proteins in a crowded environment, e.g., extracellular protein domains in confined compartments such as the synaptic cleft.}, language = {en} }