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Updated: Jun 1, 2026
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Imaging G-protein Coupled Receptor (GPCR)-mediated Signaling Events that Control Chemotaxis of Dictyostelium Discoideum
Published on: September 20, 2011
Core unit of chemotaxis signaling complexes.
Mingshan Li1, Gerald L Hazelbauer
1Department of Biochemistry, 117 Schweitzer Hall, University of Missouri, Columbia, MO 65211, USA.
Summary
Researchers identified the core unit of bacterial chemotaxis signaling complexes. This minimal unit, a 2:2:1 organization of receptor trimers of dimers, CheW, and CheA dimers, explains kinase activation and cooperativity in cell movement.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Bacterial chemotaxis relies on signaling complexes involving chemoreceptors, histidine kinase CheA, and coupling protein CheW.
- These complexes exhibit greatly enhanced kinase activity under receptor control, crucial for cellular responses.
Purpose of the Study:
- To define the minimal physical unit responsible for kinase activity within chemotaxis signaling complexes.
- To characterize the structure and stoichiometry of this core unit using the Tar chemoreceptor from Escherichia coli.
Main Methods:
- Utilized nanodisc technology to render the Tar chemoreceptor water-soluble for biochemical analysis.
- Measured saturable binding of CheA and CheW to receptor dimers.
- Purified and characterized the core units of signaling complexes.
Main Results:
- Purified complexes showed robust kinase activation, comparable to native membrane-bound complexes.
- The core unit's stoichiometry was determined to be two receptor trimers of dimers, two CheW, and one CheA dimer (2:2:1).
- This 2:2:1 organization explains the observed cooperativity and interdimer influence in signaling.
Conclusions:
- The 2:2:1 organization represents the fundamental structural and functional unit of bacterial chemotaxis signaling complexes.
- Hexagonal arrays of signaling complexes are likely assembled from this core unit.
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