title: Mechanism of activation for transcription factor PhoB suggested by different modes of dimerization in the inactive and active states.
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.
authors.affiliation: Center for Advanced Biotechnology and Medicine, Piscataway, NJ 08854, USA.
authors.forename: Priti
authors.initials: P
authors.lastname: Bachhawat
authors.forename: G V T
authors.initials: GV
authors.lastname: Swapna
authors.forename: Gaetano T
authors.initials: GT
authors.lastname: Montelione
authors.forename: Ann M
authors.initials: AM
authors.lastname: Stock
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D003461:Crystallography; D019281:Dimerization; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D010766:Phosphorylation; D017433:Protein Structure, Secondary; D012996:Solutions / Q000737:chemistry; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D012996:Solutions; D014157:Transcription Factors; C061278:PhoB protein, Bacteria