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Engineering an Osmosensor by Pivotal Histidine Positioning within Disordered Helices.
Madhubrata Ghosh1, Loo Chien Wang2, Roland G Huber3
1Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, Nanos, Singapore 138669, Singapore.
Structure (London, England : 1993)
|December 4, 2018
Summary
Histidine kinases (HKs) use a "double-clamp" switch mechanism to sense environmental changes like osmolality and pH. This mechanism regulates their autophosphorylation activity, providing a universal model for HK function.
Area of Science:
- Biochemistry
- Molecular Biology
- Microbiology
Background:
- Histidine kinases (HKs) are crucial sensors that convert environmental signals into cellular responses.
- The EnvZ histidine kinase senses both osmolality and cellular pH.
- Previous work identified osmolyte-induced stabilization of the EnvZ helical backbone near His243.
Purpose of the Study:
- To elucidate the mechanism by which backbone stabilization near His243 enhances autophosphorylation.
- To describe how the His-Asp/Glu dyad integrates environmental signals.
- To propose a universal model for histidine kinase regulation.
Main Methods:
- High-resolution structural analysis
- Biochemical assays to measure autophosphorylation
- Mutagenesis studies
Main Results:
- Backbone stabilization alters the microenvironment of His243, relieving inhibition and promoting autophosphorylation.
- The conserved His-Asp/Glu dyad acts as an integrative node for sensing both osmolality and pH.
- A
- double-clamp
- switch model explains the dual-sensing capability.
Conclusions:
- The
- double-clamp
- switch model provides a mechanistic understanding of EnvZ function.
- This model is applicable to a wide range of histidine kinases due to the conserved His-Asp/Glu dyad.
- The study offers a universal framework for histidine kinase regulation.
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