pH-dependent structural change of the extracellular sensor domain of the DraK histidine kinase from Streptomyces coelicolor

► We described the biochemical and biophysical properties of the extracellular sensory domain (ESD) of DraK histidine kinase. ► The ESD of DraK showed a reversible pH-dependent conformational change in a wide pH range. ► The E83 is an important residue for the pH-dependent conformational change.