PMID:1316901

Citation	Rahav-Manor, O, Carmel, O, Karpel, R, Taglicht, D, Glaser, G, Schuldiner, S and Padan, E (1992) NhaR, a protein homologous to a family of bacterial regulatory proteins (LysR), regulates nhaA, the sodium proton antiporter gene in Escherichia coli.J. Biol. Chem. 267:10433-8
Abstract	On the basis of protein homology, nhaR has previously been shown to belong to a large family of regulatory proteins, the LysR family (Henikoff, S., Haughn, G.W., Calvo, J.M., and Wallace, J.C. (1988) Proc. Natl. Acad. Sci. U. S. A. 85, 6602-6606). In this work we show that nhaR is a regulator of nhaA, a gene encoding a Na+/H+ antiporter in Escherichia coli. Multicopy plasmid bearing nhaR enhances the Na(+)-dependent induction of a chromosomal nhaA'-'lacZ fusion. Extracts derived from cells overexpressing nhaR exhibit specific DNA binding capacity to the upstream sequences of nhaA. Construction of an nhaR deletion mutant (OR100) shows that nhaR is required in addition to nhaA to tolerate the extreme conditions under which nhaA is indispensable. Whereas OR100 grows like the wild type at neutral pH even at high Na+ concentrations (700 mM), it becomes much more sensitive to Na+ (greater than 300 mM) at pH 8.5; furthermore, OR100 is more sensitive to Li+ (100 mM) than the wild type. Nevertheless, the phenotype of OR100, which is more resistant to Na+, Li+, and alkaline pH than a delta nhaA strain (NM81), implies that the regulation exerted by nhaR is not complete and that some expression of nhaA exists in OR100. Accordingly, the effect of nhaR in cells is dependent on the level of nhaA. OR200, a nhaA and nhaR deletion mutant, has the same phenotype as NM81. Multicopy plasmid bearing nhaR does not change the phenotype of either OR200 or NM81. On the other hand, multicopy nhaA renders the cells Li(+)- and and Na(+)-resistant even without nhaR.
Links	PubMed
Keywords	Agrobacterium tumefaciens; Amino Acid Sequence; Bacterial Proteins; Base Sequence; Blotting, Southern; Carrier Proteins; Chromosomes, Bacterial; DNA, Bacterial; DNA-Binding Proteins; Escherichia coli; Escherichia coli Proteins; Genes, Bacterial; Molecular Sequence Data; Phenotype; Plasmids; Sequence Homology, Nucleic Acid; Sodium-Hydrogen Antiporter; Transcription Factors
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Phenotype Annotations

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Phenotype of	Taxon Information	Genotype Information (if known)	Condition Information	OMP ID	OMP Term Name	ECO ID	ECO Term Name	Notes	Status
a mutation or genetic difference within a strain	Taxon: Escherichia coli Strain: K-12 Substrain: OR200 NCBI Taxon ID: 83333	Genotype of Reference Strain: nhaA nhaR	Reference Condition:			ECO:0000182	in vitro culture assay data	Sensitive to Li +
a mutation or genetic difference within a strain	Taxon: Escherichia coli Strain: K-12 Substrain: NCBI Taxon ID: 83333	Genotype of Reference Strain: nhaA Genotype of Experimental Strain : nhaA(del)	Reference Condition:			ECO:0000182	in vitro culture assay data	Sensitivity to Li +.
a mutation or genetic difference within a strain	Taxon: Escherichia coli Strain: K-12 Substrain: OR100/pKR225 and OR200/pKR225 NCBI Taxon ID: 83333	Genotype of Reference Strain: nhaA Genotype of Experimental Strain : nhaA multicopy	Reference Condition:			ECO:0000182	in vitro culture assay data	Resistance to Li +
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