PMID: 16154092 , Related PDB id: 1ZES

Authors:

Bachhawat P, Swapna GV, Montelione GT, Stock AM

Title:

Mechanism of activation for transcription factor PhoB suggested by different modes of dimerization in the inactive and active states.

Journal:

Structure. 2005 Sep;13(9):1353-63.

Abstract:

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 alpha4-beta5-alpha5 faces, while the effector domains bind to DNA direct repeats with tandem symmetry, implying a loss of intramolecular interactions.