Untersuchung der Funktion von SMC Proteinen bei der Chromosomensegregation und DNA Reparatur

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SMC (structural maintenance of chromosomes) proteins are key players in a variety of essential chromosome dynamics in all cells from bacteria to man. We are studying the prokaryotic SMC protein that acts in a complex with ScpA and ScpB proteins. The SMC complex is essential for chromosome compaction and segregation, and localizes to two distinct sites on the nucleoid (containing the chromosome), one in each cell half. Our data suggest that the SMC complex locally condenses newly replicated DNA in the subcellular centres, where it appears to form rosette-like super structures. Purified SMC binds to DNA as a ring like structure, but it is unclear how it condenses DNA. We have also found that the SMC complex interacts with topoisomerase IV at a genetic level, and has a strong influence on global protein synthesis. We will use DNA arrays to investigate if this effect is based on an effect of SMC on transcription. We will use various biochemical techniques to elucidate the exact mode of DNA binding and function for SMC protein. Protein domains will be swapped with the RecN SMC protein that binds to ssDNA rather than to dsDNA, to elucidate the different binding modes. Advanced fluorescence microscopy techniques will be employed to find out how the subcellular centres are formed, how and where in the cell SMC is loaded onto DNA, and when it interacts with ScpA and ScpB.