Funktion des Fumaratsensors DcuS von Escherichia coli in vivo und in vitro

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In the facultative anaerobic Escherichia coli the fumarate sensor DcuSR has been identified, which represents a transcriptional regulator for the switch from aerobic to anaerobic respiration. DcuSR is a two-component regulatory system consisting of membraneous sensor (DcuS) and a cytoplasmic regulator (DcuR). In spite of the significance and prevalence of sensors of this type in bacteria, is the mechanism of signal recognition and transduction is unknown. Structure determination of the periplasmic domain is in progress (cooperation AG Griesinger). The aim of the proposal is the study of reactions which are required for the signal transduction from the periplasm to the membrane domain of DcuS. Periplasmic and membraneous domains of DcuS which are essential for signal transduction will be identified. The domains and their function will be characterised biochemically in the isolated and reconstituted protein, and in vivo by molecular biological methods. These functional studies, combined with the first strutural informations on the ligand binding domain, should improve our understanding of signal transduction by two-component sensors (see accompanying proposal "DcuS structure" by Unden/Griesinger/Baldus).