Cytoplasmic sensing by the inner membrane histidine kinase EnvZ

Yong Hwee Foo, Yunfeng Gao, Hongfang Zhang, Linda Kenney

Research output: Contribution to journalReview article

20 Citations (Scopus)

Abstract

Two-component regulatory systems drive signal transduction in bacteria. The simplest of these employs a membrane sensor kinase and a cytoplasmic response regulator. Environmental sensing is typically coupled to gene regulation. The histidine kinase EnvZ and its cognate response regulator OmpR regulate expression of outer membrane proteins (porins) in response to osmotic stress. We used hydrogen:deuterium exchange mass spectrometry to identify conformational changes in the cytoplasmic domain of EnvZ (EnvZc) that were associated with osmosensing. The osmosensor localized to a seventeen amino acid region of the four-helix bundle of the cytoplasmic domain and flanked the His243 autophosphorylation site. High osmolality increased autophosphorylation of His243, suggesting that these two events were linked. The transmembrane domains were not required for osmosensing, but mutants in the transmembrane domains altered EnvZ activity. A photoactivatable fusion protein composed of EnvZc fused to the fluorophore mEos2 (EnvZc-mEos2) was as capable as EnvZc in supporting OmpR-dependent ompF and ompC transcription. Over-expression of EnvZc reduced activity, indicating that the EnvZ/OmpR system is not robust. Our results support a model in which osmolytes stabilize helix one in the four-helix bundle of EnvZ by increased hydrogen bonding of the peptide backbone, increasing autophosphorylation and downstream signaling. The likelihood that additional histidine kinases use similar cytoplasmic sensing mechanisms is discussed.

Original languageEnglish (US)
Pages (from-to)119-129
Number of pages11
JournalProgress in Biophysics and Molecular Biology
Volume118
Issue number3
DOIs
StatePublished - Sep 1 2015
Externally publishedYes

Fingerprint

Osmoregulation
Porins
Membranes
Deuterium
Hydrogen Bonding
Osmolar Concentration
Hydrogen
Signal Transduction
Mass Spectrometry
Membrane Proteins
Phosphotransferases
Bacteria
Amino Acids
Peptides
Genes
Proteins
Histidine Kinase

Keywords

  • Histidine kinase
  • Hydrogen:deuterium exchange mass spectrometry
  • Osmoregulation
  • Robustness
  • Super-resolution microscopy
  • Two-component regulatory system EnvZ/OmpR

ASJC Scopus subject areas

  • Biophysics
  • Molecular Biology

Cite this

Cytoplasmic sensing by the inner membrane histidine kinase EnvZ. / Foo, Yong Hwee; Gao, Yunfeng; Zhang, Hongfang; Kenney, Linda.

In: Progress in Biophysics and Molecular Biology, Vol. 118, No. 3, 01.09.2015, p. 119-129.

Research output: Contribution to journalReview article

Foo, Yong Hwee ; Gao, Yunfeng ; Zhang, Hongfang ; Kenney, Linda. / Cytoplasmic sensing by the inner membrane histidine kinase EnvZ. In: Progress in Biophysics and Molecular Biology. 2015 ; Vol. 118, No. 3. pp. 119-129.
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