EPR Spectroscopy Detects Various Active State Conformations of the Transcriptional Regulator CueR

The interactions between proteins and their specific DNA sequences are the basis of many cellular processes. Hence, developing methods to build an atomic level picture of these interactions helps improve our understanding of key cellular mechanisms. CueR is an Escherichia coli copper-sensing transcription regulator. The inhibition of copper-sensing transcription regulators can kill pathogens, without harming the host. Several spectroscopic studies and crystallographic data have suggested that changes in the conformation of both the DNA and the protein control transcription. However, due to the inadequate resolution of these methods, the exact number of active conformations of CueR has not been determined. Resolving the structure of CueR in its active state is highly important for the development of specific inhibitors. Herein, the potential of double-histidine (dHis)-based Cu ^II spin labeling for the identification of various conformational states of CueR during transcription is shown.