@article{OwenSauerGaus2012, author = {Owen, Dylan M. and Sauer, Markus and Gaus, Katharina}, title = {Fluorescence localization microscopy}, series = {Communicative \& Integrative Biology}, volume = {5}, journal = {Communicative \& Integrative Biology}, number = {4}, doi = {10.4161/cib.20348}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-124416}, pages = {345-349}, year = {2012}, abstract = {Localization microscopy techniques are super-resolution fluorescence imaging methods based on the detection of individual molecules. Despite the relative simplicity of the microscope setups and the availability of commercial instruments, localization microscopy faces unique challenges. While achieving super-resolution is now routine, issues concerning data analysis and interpretation mean that revealing novel biological insights is not. Here, we outline why data analysis and the design of robust test samples may hold the key to harness the full potential of localization microscopy.}, language = {en} } @article{LandoEndesfelderBergeretal.2012, author = {Lando, David and Endesfelder, Ulrike and Berger, Harald and Subramanian, Lakxmi and Dunne, Paul D. and McColl, James and Klenerman, David and Carr, Antony M. and Sauer, Markus and Allshire, Robin C. and Heilemann, Mike and Laue, Ernest D.}, title = {Quantitative single-molecule microscopy reveals that CENP-A\(^{Cnp1}\) deposition occurs during G2 in fission yeast}, series = {Open Biology}, volume = {2}, journal = {Open Biology}, number = {120078}, doi = {10.1098/rsob.120078}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-134682}, year = {2012}, abstract = {The inheritance of the histone H3 variant CENP-A in nucleosomes at centromeres following DNA replication is mediated by an epigenetic mechanism. To understand the process of epigenetic inheritance, or propagation of histones and histone variants, as nucleosomes are disassembled and reassembled in living eukaryotic cells, we have explored the feasibility of exploiting photo-activated localization microscopy (PALM). PALM of single molecules in living cells has the potential to reveal new concepts in cell biology, providing insights into stochastic variation in cellular states. However, thus far, its use has been limited to studies in bacteria or to processes occurring near the surface of eukaryotic cells. With PALM, one literally observes and 'counts' individual molecules in cells one-by-one and this allows the recording of images with a resolution higher than that determined by the diffraction of light (the so-called super-resolution microscopy). Here, we investigate the use of different fluorophores and develop procedures to count the centromere-specific histone H3 variant CENP-A\(^{Cnp1}\) with single-molecule sensitivity in fission yeast (Schizosaccharomyces pombe). The results obtained are validated by and compared with ChIP-seq analyses. Using this approach, CENP-A\(^{Cnp1}\) levels at fission yeast (S. pombe) centromeres were followed as they change during the cell cycle. Our measurements show that CENP-A(Cnp1) is deposited solely during the G2 phase of the cell cycle.}, language = {en} } @article{VogelLoeschbergerSaueretal.2011, author = {Vogel, Benjamin and L{\"o}schberger, Anna and Sauer, Markus and Hock, Robert}, title = {Cross-linking of DNA through HMGA1 suggests a DNA scaffold}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68865}, year = {2011}, abstract = {Binding of proteins to DNA is usually considered 1D with one protein bound to one DNA molecule. In principle, proteins with multiple DNA binding domains could also bind to and thereby cross-link different DNA molecules. We have investigated this possibility using high-mobility group A1 (HMGA1) proteins, which are architectural elements of chromatin and are involved in the regulation of multiple DNA-dependent processes. Using direct stochastic optical reconstruction microscopy (dSTORM), we could show that overexpression of HMGA1a-eGFP in Cos-7 cells leads to chromatin aggregation. To investigate if HMGA1a is directly responsible for this chromatin compaction we developed a DNA cross-linking assay. We were able to show for the first time that HMGA1a can cross-link DNA directly. Detailed analysis using point mutated proteins revealed a novel DNA cross-linking domain. Electron microscopy indicates that HMGA1 proteins are able to create DNA loops and supercoils in linearized DNA confirming the cross-linking ability of HMGA1a. This capacity has profound implications for the spatial organization of DNA in the cell nucleus and suggests cross-linking activities for additional nuclear proteins.}, subject = {DNA}, language = {en} }