Structural light microscopy - single molecule spectroscopy
Our long-term goal is to interface a large set of tools with our home-built, highly sensitive equipment to study structure and dynamics, even of heterogeneous biological systems such as nuclear pore complexes, chromatin, and transcription, in 4D
Combining super-resolution microscopy and single-molecule spectroscopy with advanced chemical biology concepts, can permit to study the plasticity of nuclear pore complexes at molecular resolution with high spatial and temporal resolution
The Lemke group combines advanced microscopy with modern chemical biology tools to elucidate the nature of naturally unfolded proteins in biological systems and disease mechanisms.
Previous and current research
Currently, more than 50 000 protein structures with atomic resolution are available from the protein databank. However, even if all 3D protein structures were available, our view of the molecular building blocks of cellular function would still be incomplete as we now know that many proteins are intrinsically disordered, which means that they are unfolded in their native state. Interestingly, the estimated percentage of intrinsically disordered proteins (IDPs) grows with the complexity of the organism (eukaryotes ≈ 50%). In a modern view of systems biology, these disordered proteins are believed to be multi-functional signalling hubs and their ability to adopt multiple conformations is considered a major driving force behind their evolution and enrichment in eukaryotes.
While the importance of IDPs in biology is now well established, many common strategies for probing protein structure are incompatible with molecular disorder and the highly dynamic nature of those systems. In contrast, single molecule techniques, which directly probe the distribution of molecular events, can reveal important mechanisms that otherwise remain obscured. In particular, single molecule fluorescence studies allow probing of molecular structures and dynamics at near atomic scale with exceptional time resolution. While such experiments are even possible in the natural environment of the entire cell, single molecule fluorescence studies require labelling with special fluorescent dyes, which still hampers the broad application of this technique. In our laboratory we are utilising a large spectrum of chemical biology and state-of-the-art protein engineering tools to overcome this limitation, with genetically encoding unnatural amino acids as one of our primary strategies. With a focus on studying biological questions, we also continue to develop new methods and recruit techniques from other disciplines (such as microfluidics), whenever they promise to assist our overall goal of improving our biological understanding.
Future projects and goals
Recent studies have shown that even the building blocks of some of the most complex and precise machines with an absolute critical role to survival of the cell are largely built from IDPs. For example, many nucleoporins are known to have central roles in the nuclear pore complex, but also in chromatin organisation, epigenetic mechanisms, transcription and oncogenesis. How this multifunctionality can be encoded into protein disorder is a central question in biology. We aim to explore the physical and molecular rationale behind the fundamental role of IDPs by combining molecular biology and protein engineering tools with single molecule biophysics.