Characterization of the Catalytic Activities of the PhoQ Histidine Protein Kinase of
            <i>Salmonella enterica</i>
            Serovar Typhimurium

Montagne, Martin; Martel, Alexandre; Moual, Hervé Le

doi:10.1128/jb.183.5.1787-1791.2001

Cited by 57 publications

(58 citation statements)

References 24 publications

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“…Results from the EnvZ/OmpR system have been extended to other two-component regulatory systems, leading to the conclusion that phosphatase activity of the sensor kinase is the step regulated or altered by signal input (15)(16)(17)(18)(19). * This work was supported by National Institutes of Health Grant GM58746 and National Science Foundation Grant MCB9904658.…”

Section: Ompcmentioning

confidence: 99%

“…Unphosphorylated OmpR does not play a role in porin gene expression, because envZ deletion strains are effectively OmpF Ϫ OmpC Ϫ (14). Results from the EnvZ/OmpR system have been extended to other two-component regulatory systems, leading to the conclusion that phosphatase activity of the sensor kinase is the step regulated or altered by signal input (15)(16)(17)(18)(19). …”

mentioning

confidence: 99%

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Phosphorylation Alters the Interaction of the Response Regulator OmpR with Its Sensor Kinase EnvZ

Mattison¹,

Kenney

2002

Journal of Biological Chemistry

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OmpR and EnvZ comprise a two-component system that regulates the porin genes ompF and ompC in response to changes in osmolarity. EnvZ is autophosphorylated by intracellular ATP on a histidine residue, and it transfers the phosphoryl group to an aspartic acid residue of OmpR. EnvZ can also dephosphorylate phospho-OmpR (OmpR-P) to control the cellular level of OmpR-P. At low osmolarity, OmpR-P levels are low because of either low EnvZ kinase or high EnvZ phosphatase activities. At high osmolarity, OmpR-P is elevated. It has been proposed that EnvZ phosphatase is the activity that is regulated by osmolarity. OmpR is a twodomain response regulator; phosphorylation of OmpR increases its affinity for DNA, and DNA binding stimulates phosphorylation. The step that is affected by DNA depends upon the phosphodonor employed. In the present work, we have used fluorescence anisotropy and phosphotransfer assays to examine OmpR interactions with EnvZ. Our results indicate that phosphorylation greatly reduces the affinity of OmpR for the kinase, whereas DNA does not affect their interaction. The results presented cast serious doubts on the role of the EnvZ phosphatase in response to signaling in vivo.The predominant paradigm for signal transduction in prokaryotes is the two-component regulatory system (see Ref. 1 for reviews and references). The first component is a sensor kinase, often a membrane protein, which senses the appropriate environmental signal and is phosphorylated from intracellular ATP on a histidine residue. The sensor phosphokinase then transfers the phosphoryl group to an aspartic acid residue of the second component, the response regulator. Phosphorylation of the response regulator generally leads to its activation, often by increasing its affinity for DNA with a subsequent effect on transcription. In a postulated second level of regulation, it has been suggested that the sensor kinase can also stimulate dephosphorylation of the phosphorylated response regulator via a phosphatase activity, thus limiting the level of the activated regulator and resetting the system.The two-component regulatory system that governs expression of the outer membrane porins OmpF and OmpC consists of the sensor kinase EnvZ and the response regulator OmpR. Activation of EnvZ by an unknown signal, related to the osmolarity of the growth medium, leads to phosphorylation of OmpR at aspartate 55 (2-4). Phosphorylation of OmpR results in an increased affinity for the regulatory regions upstream from the ompF and ompC genes (5-8). Recent in vitro studies demonstrated that the corollary is also true, i.e. the presence of DNA increases the level of OmpR phosphorylation (9, 10). As a result of these studies, we proposed that OmpR exists as an equilibrium mixture of four distinct states (see Fig. 1): unphosphorylated OmpR (A), phosphorylated OmpR (B), unphosphorylated OmpR bound to DNA with low affinity (C), and phosphorylated OmpR bound to DNA with high affinity (D). A similar model has been proposed for the single-domain response regulator Ch...

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Section: Ompcmentioning

confidence: 99%

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confidence: 99%

Phosphorylation Alters the Interaction of the Response Regulator OmpR with Its Sensor Kinase EnvZ

Mattison¹,

Kenney

2002

Journal of Biological Chemistry

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“…The Mg 2ϩ sensor PhoQ (2) controls the phosphorylated state of the response regulator PhoP by a combination of autokinase, phosphotransferase, and phospho-PhoP phosphatase activities (3)(4)(5): low Mg 2ϩ favors phosphorylation of the PhoP protein and transcription of PhoP-activated genes (2,6), whereas high Mg 2ϩ promotes dephosphorylation of phospho-PhoP, thereby preventing expression of PhoP-activated genes (2,3). Low Mg 2ϩ also stimulates transcription of genes under the control of the PmrA/PmrB two-component system (6) in a mechanism that involves the PhoP-activated PmrD protein (7) promoting the phosphorylated state of the PmrA protein (8).…”

Section: ؉mentioning

confidence: 99%

Signal-dependent Binding of the Response Regulators PhoP and PmrA to Their Target Promoters in Vivo

Shin

Groisman

2005

Journal of Biological Chemistry

100

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“…5,6) Based on this model, we investigated membrane-bound PhoQ autophosphorylation as previously described. 14) E. coli BL21(DE3)/pMHK028 (the phoQ expression strain) was grown at 37 C in an LB medium and induced with IPTG. Membrane-bound PhoQ was prepared as described in the Materials and Method sections.…”

Section: Mutant Scanning Of Mg 2þ Sensor Phoq On Mgrb Expressionmentioning

confidence: 99%

Isolation and Molecular Characterization of the Locked-on Mutant of Mg²⁺Sensor PhoQ inEscherichia coli

Minagawa

Okura

Tsuchitani

et al. 2005

Bioscience, Biotechnology, and Biochemistry

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Characterization of the Catalytic Activities of the PhoQ Histidine Protein Kinase of Salmonella enterica Serovar Typhimurium

Abstract: Studies of

Cited by 57 publications

References 24 publications

Phosphorylation Alters the Interaction of the Response Regulator OmpR with Its Sensor Kinase EnvZ

Phosphorylation Alters the Interaction of the Response Regulator OmpR with Its Sensor Kinase EnvZ

Signal-dependent Binding of the Response Regulators PhoP and PmrA to Their Target Promoters in Vivo

Isolation and Molecular Characterization of the Locked-on Mutant of Mg²⁺Sensor PhoQ inEscherichia coli

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Characterization of the Catalytic Activities of the PhoQ Histidine Protein Kinase of Salmonella enterica Serovar Typhimurium

Abstract: Studies of

Cited by 57 publications

References 24 publications

Phosphorylation Alters the Interaction of the Response Regulator OmpR with Its Sensor Kinase EnvZ

Phosphorylation Alters the Interaction of the Response Regulator OmpR with Its Sensor Kinase EnvZ

Signal-dependent Binding of the Response Regulators PhoP and PmrA to Their Target Promoters in Vivo

Isolation and Molecular Characterization of the Locked-on Mutant of Mg2+Sensor PhoQ inEscherichia coli

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Isolation and Molecular Characterization of the Locked-on Mutant of Mg²⁺Sensor PhoQ inEscherichia coli