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Signaling Consequences of Structural Lesions that Alter the Stability of Chemoreceptor Trimers of Dimers
- Source :
- Journal of molecular biology. 429(6)
- Publication Year :
- 2016
-
Abstract
- Residues E402 and R404 of the Escherichia coli serine chemoreceptor, Tsr, appear to form a salt bridge that spans the interfaces between neighboring dimers in the Tsr trimer of dimers, a key structural component of receptor core signaling complexes. To assess their functional roles, we constructed full sets of single amino acid replacement mutants at E402 and R404 and characterized their signaling behaviors with a suite of in vivo assays. Our results indicate that the E402 and R404 residues of Tsr play their most critical signaling roles at their inner locations near the trimer axis where they likely participate in stabilizing the trimer-of-dimer packing and the kinase-ON state of core signaling complexes. Mutant receptors with a variety of side-chain replacements still accessed both the ON and OFF signaling states, suggesting that core signaling complexes produce kinase activity over a range of receptor conformations and dynamic motions. Similarly, the kinase-OFF state may not be a discrete conformation but rather a range of structures outside the range of those suitable for kinase activation. Consistent with this idea, some structural lesions at both E402 and R404 produced signaling behaviors that are not compatible with discrete two-state models of core complex signaling states. Those lesions might stabilize intermediate receptor conformations along the OFF-ON energy landscape. Amino acid replacements produced different constellations of signaling defects at each residue, indicating that they play distinct structure-function roles. R404, but not E402, was critical for high signal cooperativity in the receptor array.
- Subjects :
- 0301 basic medicine
Stereochemistry
030106 microbiology
DNA Mutational Analysis
Methyl-Accepting Chemotaxis Proteins
Trimer
Cooperativity
Article
Serine
03 medical and health sciences
Structural Biology
Escherichia coli
Kinase activity
Phosphorylation
Molecular Biology
chemistry.chemical_classification
Chemistry
Amino acid
030104 developmental biology
Förster resonance energy transfer
Amino Acid Substitution
Biophysics
Mutagenesis, Site-Directed
Mutant Proteins
Salt bridge
Signal transduction
Protein Multimerization
Protein Processing, Post-Translational
Signal Transduction
Subjects
Details
- ISSN :
- 10898638
- Volume :
- 429
- Issue :
- 6
- Database :
- OpenAIRE
- Journal :
- Journal of molecular biology
- Accession number :
- edsair.doi.dedup.....e7368256fd974c22e208df1f796f9fa2