NhaR, a protein homologous to a family of bacterial regulatory proteins (LysR), regulates nhaA, the sodium proton antiporter gene in Escherichia coli.

Rahav‐Manor, O.; Carmel, O.; Karpel, R; Taglicht, Daniel; Glaser, Gad; Schuldiner, Shimon; Padan, Etana

doi:10.1016/s0021-9258(19)50037-0

Cited by 83 publications

(21 citation statements)

References 29 publications

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“…Most of the LysR-family proteins activate gene expression at one or more loci, while negatively regulating the expression of their own genes. The activities controlled by the LysR proteins include amino acid biosynthesis, CO2 fixation, ion transport, antibiotic resistance, virulence (Vibrio cholerae), the initiation of nodulation and chromosomal replication (Henikoff et al, 1988 and references therein;Lindquist et al, 1989;Goldberg et al, 1991;Th6ny et al, 1991;Viale et al, 1991;Rahiv-Manor et al, 1992). The capacity of a number of these proteins to respond to changes in cofactor concentrations by binding some promoters more tightly and simultaneously binding others less tightly, raises the interesting mechanistic question of whether they possess more than one DNA-binding site, or more than one mode of DNA binding.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the CysB protein of Klebsiella aerogenes: direct evidence that N-acetylserine rather than O-acetylserine serves as the inducer of the cysteine regulon

Lynch

Tyrrell

Smerdon

et al. 1994

Biochemical Journal

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The cysB gene of Klebsiella aerogenes has been cloned, sequenced and shown to complement the cysteine auxotrophic phenotype of Escherichia coli cysB mutants. The K. aerogenes cysB gene is predicted to encode a protein of 324 amino acid residues that shares approx. 95% sequence similarity with the Salmonella typhimurium and E. coli CysB proteins. Gel-retardation assays demonstrate that the purified protein binds to DNA fragments containing either the K. aerogenes cysb promoter or the S. typhimurium cysJIH promoter. Acetylserine enhances CysB binding to the cysJIH promoter fragment while diminishing its binding to the cysB promoter fragment. Fluorescence-emission-spectroscopy measurements suggest strongly that N-acetylserine binds to CysB apoprotein but that O-acetylserine does not, and support the notion that N-acetylserine is the physiological inducer of cysteine biosynthesis.

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Section: Introductionmentioning

confidence: 99%

Characterization of the CysB protein of Klebsiella aerogenes: direct evidence that N-acetylserine rather than O-acetylserine serves as the inducer of the cysteine regulon

Lynch

Tyrrell

Smerdon

et al. 1994

Biochemical Journal

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“…Given the importance of Na + to living systems, it seems likely that most species will carry sensors for this alkali metal ion that evaluate its concentration and regulate the expression of genes relevant to Na + homeostasis or exploitation. The discovery and experimental validation of a riboswitch class that selectively responds to Na + helps address the puzzling observation that only one experimentally validated protein factor, NhaR, has been proved to function as a Na + -responsive gene control factor 18 .…”

Section: Discussionmentioning

confidence: 99%

“…There are very few descriptions of protein factors that both selectively sense Na + and regulate gene expression. The only experimentally validated Na + -selective gene control factor is the NhaR protein from Escherichia coli 18 , although other proteins have been proposed to serve similar functions 19 . The dearth of reported Na + -selective protein genetic factors in bacteria could be simply due to limited exploration of such regulatory systems.…”

Section: Mainmentioning

confidence: 99%

Na+ riboswitches regulate genes for diverse physiological processes in bacteria

et al. 2022

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Organisms presumably have mechanisms to monitor and physiologically adapt to changes in cellular Na+ concentrations. Only a single bacterial protein has previously been demonstrated to selectively sense Na+ and regulate gene expression. Here we report a riboswitch class, previously called the ‘DUF1646 motif’, whose members selectively sense Na+ and regulate the expression of genes relevant to sodium biology. Many proteins encoded by Na+-riboswitch-regulated genes are annotated as metal ion transporters, whereas others are involved in mitigating osmotic stress or harnessing Na+ gradients for ATP production. Na+ riboswitches exhibit dissociation constants in the low mM range, and strongly reject all other alkali and alkaline earth ions. Likewise, only Na+ triggers riboswitch-mediated transcription and gene expression changes. These findings reveal that some bacteria use Na+ riboswitches to monitor, adjust and exploit Na+ concentrations and gradients, and in some instances collaborate with c-di-AMP riboswitches to coordinate gene expression during osmotic stress.

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“…These candidate proteins are described in Table 1 and include homologs of regulators NhaR (VP0527), OmpR (VP0154), and TorR (VP1032). NhaR and OmpR had previously been shown in Escherichia coli to be involved in osmotic stress (35)(36)(37)(38)(39)(40). NhaR, a LysR-type transcriptional regulator, shows 62% amino acid homology to NhaR from E. coli K-12, OmpR showed 84% amino acid identity and TorR 57% amino acid homology to OmpR and TorR respectively from E. coli.…”

Section: Identification Of Putative Regulators Of the Ectoine Biosynt...mentioning

confidence: 99%

NhaR, LeuO and H-NS are part of an expanded regulatory network for ectoine biosynthesis expression

Lichty

Gregory

Boyd

2022

Preprint

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Bacteria accumulate compatible solutes to maintain cellular turgor pressure when exposed to high salinity. In the marine halophile Vibrio parahaemolyticus, the compatible solute ectoine is biosynthesized de novo, which is energetically more costly than uptake; therefore, tight regulation is required. To uncover novel regulators of the ectoine biosynthesis ectABC-aspk operon, a DNA affinity pulldown of proteins interacting with the ectABC-aspk regulatory region was performed. Mass spectrometry analysis identified, amongst others, five regulators: LeuO, NhaR, OmpR, TorR, and the nucleoid associated protein H-NS. To determine their role in ectoine biosynthesis, in-frame non-polar deletions were made for each gene and PectA-gfp promoter reporter assays were performed. PectA-gfp expression was significantly repressed in the ΔleuO mutant and significantly induced in the ΔnhaR mutant compared to wild type, suggesting positive and negative regulation, respectively. Both ΔompR and ΔtorR mutants also showed induced expression of PectA-gfp, but not to the same extent as ΔnhaR. The Δhns showed no change compared to wild type. To examine whether H-NS interacts with LeuO or NhaR at the ectoine regulatory region, double deletion mutants were created. In a ΔleuO/Δhns mutant, PectA-gfp showed reduced expression, but significantly more than ΔleuO suggesting H-NS and LeuO interact to regulate ectoine expression. Whereas ΔnhaR/Δhns had no additional effect as compared to ΔnhaR suggesting NhaR regulation is independent of H-NS. Next, a PleuO-gfp reporter analysis was performed in wild type ΔleuO, Δhns, ΔleuO/Δhns and ΔtoxR, which encodes ToxR a positive regulator of leuO. PleuO-gfp showed significantly increased expression in the ΔleuO, Δhns and ΔleuO/Δhns mutants as compared to wild type, indicating both are repressors of leuO, and ΔtoxR showed reduced expression. Growth pattern analysis of the ΔleuO, Δhns, and ΔleuO/Δhns mutants in M9G 6%NaCl all showed growth defects compared to wild type, with ΔleuO/Δhns showing the greatest effect. Overall, the data show that NhaR is a negative regulator and LeuO is a positive regulator of ectoine expression and suggest LeuO is an anti-silencer of H-NS.

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NhaR, a protein homologous to a family of bacterial regulatory proteins (LysR), regulates nhaA, the sodium proton antiporter gene in Escherichia coli.

Cited by 83 publications

References 29 publications

Characterization of the CysB protein of Klebsiella aerogenes: direct evidence that N-acetylserine rather than O-acetylserine serves as the inducer of the cysteine regulon

Characterization of the CysB protein of Klebsiella aerogenes: direct evidence that N-acetylserine rather than O-acetylserine serves as the inducer of the cysteine regulon

Na+ riboswitches regulate genes for diverse physiological processes in bacteria

NhaR, LeuO and H-NS are part of an expanded regulatory network for ectoine biosynthesis expression

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