Single cell super-resolution imaging of E. coli OmpR during environmental stress

Yong Hwee Foo, Christoph Spahn, Hongfang Zhang, Mike Heilemann, Linda Kenney

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

Two-component signaling systems are a major strategy employed by bacteria, and to some extent, yeast and plants, to respond to environmental stress. The EnvZ/OmpR system in E. coli responds to osmotic and acid stress and is responsible for regulating the protein composition of the outer membrane. EnvZ is a histidine kinase located in the inner membrane. Upon activation, it is autophosphorylated by ATP and subsequently, it activates OmpR. Phosphorylated OmpR binds with high affinity to the regulatory regions of the ompF and ompC porin genes to regulate their transcription. We set out to visualize these two-components in single bacterial cells during different environmental stress conditions and to examine the subsequent modifications to the bacterial nucleoid as a result. We created a chromosomally-encoded, active, fluorescent OmpR-PAmCherry fusion protein and compared its expression levels with RNA polymerase. Quantitative western blotting had indicated that these two proteins were expressed at similar levels. From our images, it is evident that OmpR is significantly less abundant compared to RNA polymerase. In cross-sectional axial images, we observed OmpR molecules closely juxtaposed near the inner membrane during acidic and hyposomotic growth. In acidic conditions, the chromosome was compacted. Surprisingly, under acidic conditions, we also observed evidence of a spatial correlation between the DNA and the inner membrane, suggesting a mechanical link through an active DNA-OmpR-EnvZ complex. This work represents the first direct visualization of a response regulator with respect to the bacterial chromosome.

Original languageEnglish (US)
Pages (from-to)1297-1308
Number of pages12
JournalIntegrative Biology (United Kingdom)
Volume7
Issue number10
DOIs
StatePublished - Oct 1 2015
Externally publishedYes

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Escherichia coli
Membranes
Imaging techniques
DNA-Directed RNA Polymerases
Chromosomes
Bacterial Chromosomes
Porins
Proteins
Nucleic Acid Regulatory Sequences
DNA
Osmotic Pressure
Transcription
Histidine
Yeast
Bacteria
Phosphotransferases
Fusion reactions
Visualization
Genes
Adenosine Triphosphate

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry

Cite this

Single cell super-resolution imaging of E. coli OmpR during environmental stress. / Foo, Yong Hwee; Spahn, Christoph; Zhang, Hongfang; Heilemann, Mike; Kenney, Linda.

In: Integrative Biology (United Kingdom), Vol. 7, No. 10, 01.10.2015, p. 1297-1308.

Research output: Contribution to journalArticle

Foo, Yong Hwee ; Spahn, Christoph ; Zhang, Hongfang ; Heilemann, Mike ; Kenney, Linda. / Single cell super-resolution imaging of E. coli OmpR during environmental stress. In: Integrative Biology (United Kingdom). 2015 ; Vol. 7, No. 10. pp. 1297-1308.
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