Different Signaling Roles of Two Conserved Residues in the Cytoplasmic Hairpin Tip of Tsr, the
            <i>Escherichia coli</i>
            Serine Chemoreceptor

Mowery, Patricia; Ostler, Jeffery B.; Parkinson, John S.

doi:10.1128/jb.01121-08

Cited by 32 publications

(64 citation statements)

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“…Structural changes in the receptor's hairpin tip region (Fig. 1) that produce a wide range of signaling behaviors did not potentiate the CheR effect (53)(54)(55). Perhaps the receptor methylation helices, whose conformation and packing stability are under direct control by the HAMP domain, are central to the CheR effect.…”

Section: A Possible Nonequilibrium Mechanism For Cher Response Enhancmentioning

confidence: 99%

“…CheR expression from pPA810 was measured in strain UU2902; native CheR expression was measured in strain RP437. Cell samples were prepared as described by Li and Hazelbauer (34) and analyzed by SDS/PAGE and immunoblotting, as described previously (34,54). Briefly, cells were grown in tryptone broth (containing 12.5 μg/mL chloramphenicol and different concentrations of sodium salicylate inducer for pPA810 experiments) at 30°C to OD600 = 0.5.…”

Section: Methodsmentioning

confidence: 99%

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Paradoxical enhancement of chemoreceptor detection sensitivity by a sensory adaptation enzyme

Lai¹,

Han²,

Dahlquist³

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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A sensory adaptation system that tunes chemoreceptor sensitivity enables motile Escherichia coli cells to track chemical gradients with high sensitivity over a wide dynamic range. Sensory adaptation involves feedback control of covalent receptor modifications by two enzymes: CheR, a methyltransferase, and CheB, a methylesterase. This study describes a CheR function that opposes the signaling consequences of its catalytic activity. In the presence of CheR, a variety of mutant serine chemoreceptors displayed up to 40-fold enhanced detection sensitivity to chemoeffector stimuli. This response enhancement effect did not require the known catalytic activity of CheR, but did involve a binding interaction between CheR and receptor molecules. Response enhancement was maximal at low CheR:receptor stoichiometry and quantitative analyses argued against a reversible binding interaction that simply shifts the ON-OFF equilibrium of receptor signaling complexes. Rather, a short-lived CheR binding interaction appears to promote a long-lasting change in receptor molecules, either a covalent modification or conformation that enhances their response to attractant ligands.bacterial chemotaxis | receptor methyltransferase | dynamic-bundle model | signaling conformation | nonequilibrium mechanism M otile bacteria, despite their small size and simple cellular architecture, track chemical gradients in their living environments with extraordinary precision (see refs. 1 and 2 for reviews). They do so with only a handful of different proteins organized in a sensory signaling network that has stimulus integration, amplification, and memory capabilities. The extensively studied chemotaxis machinery of Escherichia coli has provided the molecular paradigm for transmembrane and intracellular signaling mechanisms in microbial chemosensory systems. This report describes a long-unrecognized activity of a central component of the E. coli chemotaxis machinery, suggesting that there are important new molecular lessons to learn from this structurally simple, yet functionally sophisticated, signaling system. E. coli senses attractant and repellent chemicals with transmembrane chemoreceptors known as methyl-accepting chemotaxis proteins (MCPs) (3). MCPs form networked arrays of signaling complexes, typically at the cell poles, that produce highly sensitive and cooperative responses to small chemoeffector concentration changes. The four MCPs of E. coli (Tsr, Tar, Tap, and Trg) have a common functional architecture comprising a periplasmic sensing domain and a cytoplasmic signaling domain (Fig. 1). An interposed HAMP domain communicates conformational changes between the sensing and signaling domains through an extended four-helix coiled-coil that contains sites for sensory adaptation adjustments of receptor signal output (4). The chemoreceptors modulate the activity of a histidine autokinase (CheA), which is stably coupled to receptors by a scaffolding protein (CheW). CheA donates its phosphoryl groups to CheY, a response regulator that in its phosphory...

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Section: A Possible Nonequilibrium Mechanism For Cher Response Enhancmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Paradoxical enhancement of chemoreceptor detection sensitivity by a sensory adaptation enzyme

Lai¹,

Han²,

Dahlquist³

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

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show abstract

“…The plasmids used in receptor-clustering assays were pVS49, a derivative of pACYC184 (13) that makes a functional fusion of CheZ to yellow fluorescent protein (YFP) under inducible arabinose control (39); pVS102, a relative of pVS49 that makes a functional YFP-CheR fusion protein under inducible arabinose control (21); and pPA801, a relative of pVS49 that makes a functional YFP-CheW fusion protein under inducible arabinose control (28).…”

Section: Methodsmentioning

confidence: 99%

“…Tsr expression from pRR53 derivatives was analyzed in strain UU1535 to avoid multiple modification states. Cells were grown and lysates analyzed by SDS-PAGE as described previously (28). Dominance, rescue, and jamming tests.…”

Section: Methodsmentioning

confidence: 99%

“…Tsr expression from pRR53 derivatives was induced with 100 M IPTG, YFP-CheZ (pVS49) was induced with 0.005% (wt/vol) L(ϩ)-arabinose, YFP-CheR (pVS102) was induced with 0.01% (wt/vol) L(ϩ)-arabinose, and YFP-CheW (pPA801) was induced with 0.004% (wt/vol) L(ϩ)-arabinose. Cells were grown in tryptone broth at 30°C to mid-exponential phase and analyzed by fluorescence microscopy as previously described (4,28).…”

Section: Methodsmentioning

confidence: 99%

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Mutational Analysis of N381, a Key Trimer Contact Residue in Tsr, the Escherichia coli Serine Chemoreceptor

Gosink¹,

Zhao²,

Parkinson³

2011

Journal of Bacteriology

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Chemoreceptors such as Tsr, the serine receptor, function in trimer-of-dimer associations to mediate chemotactic behavior in Escherichia coli. The two subunits of each receptor homodimer occupy different positions in the trimer, one at its central axis and the other at the trimer periphery. Residue N381 of Tsr contributes to trimer stability through interactions with its counterparts in a central cavity surrounded by hydrophobic residues at the trimer axis. To assess the functional role of N381, we created and characterized a full set of amino acid replacements at this Tsr residue. We found that every amino acid replacement at N381 destroyed Tsr function, and all but one (N381G) of the mutant receptors also blocked signaling by Tar, the aspartate chemoreceptor. Tar jamming reflects the formation of signaling-defective mixed trimers of dimers, and in vivo assays with a trifunctional cross-linking reagent demonstrated trimer-based interactions between Tar and Tsr-N381 mutants. Mutant Tsr molecules with a charged amino acid or proline replacement exhibited the most severe trimer formation defects. These trimer-defective receptors, as well as most of the trimercompetent mutant receptors, were unable to form ternary signaling complexes with the CheA kinase and with CheW, which couples CheA to receptor control. Some of the trimer-competent mutant receptors, particularly those with a hydrophobic amino acid replacement, may not bind CheW/CheA because they form conformationally frozen or distorted trimers. These findings indicate that trimer dynamics probably are important for ternary complex assembly and that N381 may not be a direct binding determinant for CheW/CheA at the trimer periphery.

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Methyl-accepting chemotaxis proteins: a core sensing element in prokaryotes and archaea

Ud-Din

Roujeinikova

2017

Cell. Mol. Life Sci.

151

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Chemotaxis is the directed motility by means of which microbes sense chemical cues and relocate towards more favorable environments. Methyl-accepting chemotaxis proteins (MCPs) are the most common receptors in bacteria and archaea. They are arranged as trimers of dimers that, in turn, form hexagonal arrays in the cytoplasmic membrane or in the cytoplasm. Several different classes of MCPs have been identified according to their ligand binding region and membrane topology. MCPs have been further classified based on the length and sequence conservation of their cytoplasmic domains. Clusters of membrane-embedded MCPs often localize to the poles of the cell, whereas cytoplasmic MCPs can be targeted to the poles or distributed throughout the cell body. MCPs play an important role in cell survival, pathogenesis, and biodegradation. Bacterial adaptation to diverse environmental conditions promotes diversity among the MCPs. This review summarizes structure, classification, and structure-activity relationship of the known MCP receptors, with a brief overview of the signal transduction mechanisms in bacteria and archaea.

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Different Signaling Roles of Two Conserved Residues in the Cytoplasmic Hairpin Tip of Tsr, the Escherichia coli Serine Chemoreceptor

Cited by 32 publications

References 50 publications

Paradoxical enhancement of chemoreceptor detection sensitivity by a sensory adaptation enzyme

Paradoxical enhancement of chemoreceptor detection sensitivity by a sensory adaptation enzyme

Mutational Analysis of N381, a Key Trimer Contact Residue in Tsr, the Escherichia coli Serine Chemoreceptor

Methyl-accepting chemotaxis proteins: a core sensing element in prokaryotes and archaea

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