PMID:14622424
| Citation |
Stewart, V, Chen, LL and Wu, HC (2003) Response to culture aeration mediated by the nitrate and nitrite sensor NarQ of Escherichia coli K-12. Mol. Microbiol. 50:1391-9 |
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| Abstract |
Respiratory enzyme synthesis in enterobacteria is controlled in response to electron acceptor availability. The iron-sulphur protein Fnr and the sensor-regulator proteins ArcB-ArcA control respiratory gene transcription in response to oxygen and quinone pool redox status respectively. The sensor-regulator proteins NarX-NarL and NarQ-NarP control anaerobic respiratory gene expression in response to nitrate and nitrite. Our laboratory recently engineered the lac operon to replace the primary operator O1-lac with the NarL and NarP protein binding site from the nirB operon. Expression of the lacZ gene from this construct is repressed by nitrate in Nar+ strains. Here, we found that lacZ gene expression was repressed in aerated cultures of narQ+narX null strains. This repression was not observed in narX+narQ+ or narX+narQ null strains. Thus, the NarQ sensor responds to aeration as well as to nitrate and nitrite. The NarX and NarQ sensors are composed of three distinct modules: an amino-terminal sensory module, a carboxyl-terminal transmitter module and a central module of unknown function. Experiments with NarX-NarQ hybrid proteins suggest that the NarQ protein central module is necessary for response to aeration. The physiological significance of this additional sensory role for the NarQ sensor remains obscure. |
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| Keywords |
Binding Sites; Escherichia coli/genetics; Escherichia coli/metabolism; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Gene Expression Regulation, Bacterial; Membrane Proteins/genetics; Membrane Proteins/metabolism; Nitrates/metabolism; Nitrites/metabolism; Operon; Oxidation-Reduction; Phosphoproteins/genetics; Phosphoproteins/metabolism; Protein Structure, Tertiary; Recombinant Fusion Proteins/genetics; Recombinant Fusion Proteins/metabolism; Signal Transduction |
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