Interactions of the intact FsrC membrane histidine kinase with its pheromone ligand GBAP revealed through synchrotron radiation circular dichroism

► The intact purified FsrC membrane histidine kinase was studied by SRCD spectroscopy. ► Far-UV spectra revealed that FsrC is 61% α-helical and relatively thermostable. ► Tertiary structure was found to be significantly affected upon GBAP ligand binding. ► Titration experiments revealed a calculated kd value of 2 μM. ► SRCD provides a valuable screening tool for membrane protein stability under a range of detergent conditions.