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Sensor-response regulator interactions in a cross-regulated signal transduction network
TuAnh Ngoc Huynh1, Li-Ling Chen2, Valley Stewart3
11 Food Science Graduate Group, University of California, Davis, CA, 95616-8665, USA.
Microbiology (Reading, England)
|April 16, 2015
Summary
Escherichia coli
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Two-component signal transduction systems regulate cellular responses.
- Nitrate-responsive systems in E. coli involve NarX-NarL and NarQ-NarP pairs.
- These systems exhibit complex cross-regulation.
Purpose of the Study:
- Investigate sensor dimerization and sensor-regulator interactions.
- Examine cognate and non-cognate pair interactions.
- Understand the mechanisms of cross-regulation in nitrate signaling.
Main Methods:
- Bacterial adenylate cyclase two-hybrid (BACTH) analysis.
- Intragenic complementation tests.
- Analysis of sensor dimerization and protein-protein interactions.
Main Results:
- NarX and NarQ sensors interact but do not form functional heterodimers.
- NarX and NarQ undergo intermolecular autophosphorylation.
- Differential binding affinities observed for sensor-regulator pairs (NarX-NarL, NarQ-NarL, NarQ-NarP, NarX-NarP).
- NarL effector domain inhibits NarX-NarL interaction; mutations enhance it.
Conclusions:
- Sensor dimerization and heterodimerization are distinct processes.
- Autophosphorylation mode deviates from established models.
- Asymmetrical cross-regulation is driven by varying binding affinities.
- NarL effector domain plays a role in regulating NarX-NarL interaction.
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