Response regulators (RRs), which undergo phosphorylation/dephosphorylation at aspartate residues, are highly prevalent in bacterial signal transduction. RRs typically contain an N-terminal receiver domain that regulates the activities of a C-terminal DNA binding domain in a phosphorylation-dependent manner. We present crystallography and solution NMR data for the receiver domain of Escherichia coli PhoB which show distinct 2-fold symmetric dimers in the inactive and active states. These structures, together with the previously determined structure of the C-terminal domain of PhoB bound to DNA, define the conformation of the active transcription factor and provide a model for the mechanism of activation in the OmpR/PhoB subfamily, the largest group of RRs. In the active state, the receiver domains dimerize with 2-fold rotational symmetry using their α4-β5-α5 faces, while the effector domains bind to DNA direct repeats with tandem symmetry, implying a loss of intramolecular interactions. ©2005 Elsevier Ltd All rights reserved.
Bachhawat, P., Swapna, G. V. T., Montelione, G. T., & Stock, A. M. (2005). Mechanism of activation for transcription factor PhoB suggested by different modes of dimerization in the inactive and active states. Structure, 13(9), 1353–1363. https://doi.org/10.1016/j.str.2005.06.006