Modulation of the Thermosensing Profile of the   Aspartate Receptor Tar by Covalent Modification of Its Methyl-accepting Sites

Nara, Toshifumi; Kawagishi, Ikuro; Nishiyama, So-ichiro; Homma, Michio; Imae, Yasuo

doi:10.1074/jbc.271.30.17932

Cited by 49 publications

(52 citation statements)

References 41 publications

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“…The temperature dependence of the equilibrium between the two HAMP conformations could also be an interpretative key to an understanding of the thermosensing function of Tar and Tsr (50,51).…”

Section: Discussionmentioning

confidence: 99%

Salt-driven Equilibrium between Two Conformations in the HAMP Domain from Natronomonas pharaonis

Doebber

Bordignon

Klare

et al. 2008

Journal of Biological Chemistry

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HAMP domains (conserved in histidine kinases, adenylyl cyclases, methyl-accepting chemotaxis proteins, and phosphatases) perform their putative function as signal transducing units in diversified environments in a variety of protein families. Here the conformational changes induced by environmental agents, namely salt and temperature, on the structure and function of a HAMP domain of the phototransducer from Natronomonas pharaonis (NpHtrII) in complex with sensory rhodopsin II (NpSRII) were investigated by site-directed spin labeling electron paramagnetic resonance. A series of spin labeled mutants were engineered in NpHtrII 157 , a truncated analog containing only the first HAMP domain following the transmembrane helix 2. This truncated transducer is shown to be a valid model system for a signal transduction domain anchored to the transmembrane light sensor NpSRII. The HAMP domain is found to be engaged in a "two-state" equilibrium between a highly dynamic (dHAMP) and a more compact (cHAMP) conformation. The structural properties of the cHAMP as proven by mobility, accessibility, and intra-transducer-dimer distance data are in agreement with the four helical bundle NMR model of the HAMP domain from Archaeoglobus fulgidus.

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Section: Discussionmentioning

confidence: 99%

Salt-driven Equilibrium between Two Conformations in the HAMP Domain from Natronomonas pharaonis

Doebber

Bordignon

Klare

et al. 2008

Journal of Biological Chemistry

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“…The Tar and Tsr responses to cytoplasmic pH changes, for example, depend on several residues near the HAMP-MH1 junction (25,53). Thermosensing, a property of all E. coli MCPs, could conceivably occur through temperature-dependent changes in the TM2-HAMP-methylation helix region (34)(35)(36)(37). Repellent responses to glycerol and ethylene glycol, also mediated by multiple MCPs, could involve perturbations of membrane curvature and the relative positions of the TM helices (39).…”

Section: Discussionmentioning

confidence: 99%

Phenol Sensing by Escherichia coli Chemoreceptors: a Nonclassical Mechanism

Parkinson

2011

Journal of Bacteriology

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The four transmembrane chemoreceptors of Escherichia coli sense phenol as either an attractant (Tar) or a repellent (Tap, Trg, and Tsr). In this study, we investigated the Tar determinants that mediate its attractant response to phenol and the Tsr determinants that mediate its repellent response to phenol. Tar molecules with lesions in the aspartate-binding pocket of the periplasmic domain, with a foreign periplasmic domain (from Tsr or from several Pseudomonas chemoreceptors), or lacking nearly the entire periplasmic domain still mediated attractant responses to phenol. Similarly, Tar molecules with the cytoplasmic methylation and kinase control domains of Tsr still sensed phenol as an attractant. Additional hybrid receptors with signaling elements from both Tar and Tsr indicated that the transmembrane (TM) helices and HAMP domain determined the sign of the phenol-sensing response. Several amino acid replacements in the HAMP domain of Tsr, particularly attractant-mimic signaling lesions at residue E248, converted Tsr to an attractant sensor of phenol. These findings suggest that phenol may elicit chemotactic responses by diffusing into the cytoplasmic membrane and perturbing the structural stability or position of the TM bundle helices, in conjunction with structural input from the HAMP domain. We conclude that behavioral responses to phenol, and perhaps to temperature, cytoplasmic pH, and glycerol, as well, occur through a general sensing mechanism in chemoreceptors that detects changes in the structural stability or dynamic behavior of a receptor signaling element. The structurally sensitive target for phenol is probably the TM bundle, but other behaviors could target other receptor elements.Chemotaxis, the movement of an organism toward or away from chemicals, is an important adaptive behavior of motile prokaryotes, such as Escherichia coli. Both bacteria and archaea employ chemoreceptors known as methyl-accepting chemotaxis proteins (MCPs) to monitor their chemical environments (3, 61). E. coli has four canonical MCPs: Tsr mediates attractant responses to serine and to the interspecies quorum signal, 47); Tar mediates attractant responses to aspartate and to maltose (17, 47); Tap mediates attractant responses to dipeptides and to pyrimidines (28, 31); and Trg mediates attractant responses to ribose and galactose (16). These transmembrane receptors function as homodimers of ϳ550-residue subunits, each comprising a periplasmic sensing domain, flanked by two membrane-spanning helices (TM1 and TM2), and a cytoplasmic kinase control domain (Fig. 1). The cytoplasmic region of MCPs consists of a signal-converting HAMP domain at the membrane interface and a long coiledcoil four-helix bundle (Fig. 1). The highly conserved membrane-distal tip of the cytoplasmic bundle contains residues that promote interactions with other MCP molecules, with the signaling kinase CheA, and with CheW, which couples CheA autophosphorylation activity to receptor control (4,23,50). CheA, in turn, regulates the phosphorylation state of Che...

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“…Cells with only Tsr or Tar show a wild-type thermal response, whereas cells with only Trg and Tap, at normal levels, show no thermal response (11). Cells adapt to temperature changes via the chemosensory adaptation pathway, where the activity of the receptors is modulated by changing their methylation state (4). The methylation state of the receptors also affects the direction of the thermal response.…”

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confidence: 99%

“…The thermotactic behavior of bacteria is similar to its chemotactic behavior: Cells measure thermal stimuli over time and bias their run and tumble statistics to promote movement toward their preferred temperature. Typically, an increase in temperature causes bacteria to swim smoothly, and a decrease in temperature causes bacteria to tumble (1), but the response will reverse when cells are adapted to certain chemoattractants (4,5). This stochastic strategy biases the cell's random walk, so that on average it will migrate along spatial temperature gradients (6).…”

mentioning

confidence: 99%

The thermal impulse response of Escherichia coli

Paster¹,

Ryu²

2008

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

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Swimming Escherichia coli responds to changes in temperature by modifying its motor behavior. Previous studies using populations of cells have shown that E. coli accumulate in spatial thermal gradients, but these experiments did not cleanly separate thermal responses from chemotactic responses. Here we have isolated the thermal response by studying the behavior of single, tethered cells. The motor output of cells grown at 33°C was measured at constant temperature, from 10°to 40°C, and in response to small, impulsive increases in temperature, from 23°to 43°C. The thermal impulse response at temperatures < 31°C is similar to the chemotactic impulse response: Both follow a similar time course, share the same directionality, and show biphasic characteristics. At temperatures > 31°C, some cells show an inverted response, switching from warm-to cold-seeking behavior. The fraction of inverted responses increases nonlinearly with temperature, switching steeply at the preferred temperature of 37°C.thermotaxis ͉ taxis ͉ strategy

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Modulation of the Thermosensing Profile of the Aspartate Receptor Tar by Covalent Modification of Its Methyl-accepting Sites

Cited by 49 publications

References 41 publications

Salt-driven Equilibrium between Two Conformations in the HAMP Domain from Natronomonas pharaonis

Salt-driven Equilibrium between Two Conformations in the HAMP Domain from Natronomonas pharaonis

Phenol Sensing by Escherichia coli Chemoreceptors: a Nonclassical Mechanism

The thermal impulse response of Escherichia coli

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