Structural characterization of Escherichia coli sensor histidine kinase EnvZ: The periplasmic C-terminal core domain is critical for homodimerization

Ahmad Khorchid, Masayori Inouye, Mitsuhiko Ikura

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Escherichia coli EnvZ is a membrane sensor histidine kinase that plays a pivotal role in cell adaptation to changes in extracellular osmolarity. Although the cytoplasmic histidine kinase domain of EnvZ has been extensively studied, both biochemically and structurally, little is known about the structure of its periplasmic domain, which has been implicated in the mechanism underlying its osmosensing function. In the present study, we report the biochemical and biophysical characterization of the periplasmic region of EnvZ (Ala 38-Arg162). This region was found to form a dimer in solution, and to consist of two well-defined domains: an N-terminal α-helical domain and a C-terminal core domain (Glu83-Arg 162) containing both á-helical and β-sheet secondary structures. Our pull-down assays and analytical ultracentrifugation analysis revealed that dimerization of the periplasmic region is highly sensitive to the presence of CHAPS, but relatively insensitive to salt concentration, thus suggesting the significance of hydrophobic interactions between the homodimeric subunits, Periplasmic homodimerization is mediated predominantly by the C-terminal core domain, while a regulatory function may be attributed mainly to the N-terminal α-helical domain, whose mutations have been shown previously to produce a high-osmolarity phenotype.

Original languageEnglish (US)
Pages (from-to)255-264
Number of pages10
JournalBiochemical Journal
Volume385
Issue number1
DOIs
StatePublished - Jan 1 2005

Fingerprint

Histidine
Osmolar Concentration
Escherichia coli
Phosphotransferases
Dimerization
Ultracentrifugation
Sensors
Hydrophobic and Hydrophilic Interactions
Dimers
Assays
Salts
Membranes
Phenotype
Mutation
Histidine Kinase
3-((3-cholamidopropyl)dimethylammonium)-1-propanesulfonate

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Keywords

  • Bacterial signal transduction
  • Membrane receptor
  • NMR
  • Osmolarity
  • Stress response

Cite this

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Structural characterization of Escherichia coli sensor histidine kinase EnvZ : The periplasmic C-terminal core domain is critical for homodimerization. / Khorchid, Ahmad; Inouye, Masayori; Ikura, Mitsuhiko.

In: Biochemical Journal, Vol. 385, No. 1, 01.01.2005, p. 255-264.

Research output: Contribution to journalArticle

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AB - Escherichia coli EnvZ is a membrane sensor histidine kinase that plays a pivotal role in cell adaptation to changes in extracellular osmolarity. Although the cytoplasmic histidine kinase domain of EnvZ has been extensively studied, both biochemically and structurally, little is known about the structure of its periplasmic domain, which has been implicated in the mechanism underlying its osmosensing function. In the present study, we report the biochemical and biophysical characterization of the periplasmic region of EnvZ (Ala 38-Arg162). This region was found to form a dimer in solution, and to consist of two well-defined domains: an N-terminal α-helical domain and a C-terminal core domain (Glu83-Arg 162) containing both á-helical and β-sheet secondary structures. Our pull-down assays and analytical ultracentrifugation analysis revealed that dimerization of the periplasmic region is highly sensitive to the presence of CHAPS, but relatively insensitive to salt concentration, thus suggesting the significance of hydrophobic interactions between the homodimeric subunits, Periplasmic homodimerization is mediated predominantly by the C-terminal core domain, while a regulatory function may be attributed mainly to the N-terminal α-helical domain, whose mutations have been shown previously to produce a high-osmolarity phenotype.

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