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A common dimerization interface in bacterial response regulators KdpE and TorR
Author(s) -
ToroRoman Alejandro,
Wu Ti,
Stock Ann M.
Publication year - 2005
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.051722805
Subject(s) - response regulator , histidine kinase , regulator , subfamily , biology , caulobacter crescentus , microbiology and biotechnology , phosphorylation , two component regulatory system , kinase , transcription factor , biochemistry , histidine , gene , mutant , bacterial protein , amino acid
Bacterial response regulators are key regulatory proteins that function as the final elements of so‐called two‐component signaling systems. The activities of response regulators in vivo are modulated by phosphorylation that results from interactions between the response regulator and its cognate histidine protein kinase. The level of response regulator phosphorylation, which is regulated by intra‐or extracellular signals sensed by the histidine protein kinase, ultimately determines the output response that is initiated or carried out by the response regulator. We have recently hypothesized that in the OmpR/PhoB subfamily of response regulator transcription factors, this activation involves a common mechanism of dimerization using a set of highly conserved residues in the α4–β5–α5 face. Here we report the X‐ray crystal structures of the regulatory domains of response regulators TorR (1.8 Å), Ca 2+ ‐bound KdpE (2.0 Å), and Mg 2+ /BeF 3 − ‐bound KdpE (2.2 Å), both members of the OmpR/ PhoB subfamily from Escherichia coli . Both regulatory domains form symmetric dimers in the asymmetric unit that involve the α4–β5–α5 face. As observed previously in other OmpR/PhoB response regulators, the dimer interfaces are mediated by highly conserved residues within this subfamily. These results provide further evidence that most all response regulators of the OmpR/ PhoB subfamily share a common mechanism of activation by dimerization.

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