Regulation of proline utilization in Salmonella typhimurium: Molecular characterization of the put operon, and DNA sequence of the put control region

Hahn, Donald R.; Myers, Richard S.; Kent, Craig R.; Maloy, Stanley

doi:10.1007/bf00333408

Cited by 39 publications

(34 citation statements)

References 40 publications

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“…4) There are several features of the NAD system which make it attractive for study, not the least of which is the unique bifunctional nature of the NadR repressor-transporter and its possible membrane association. There are other examples of membrane-associated regulatory proteins, such as ToxR from Vibrio cholerae, PutA from S. typhimurium, and BglS from E. coli (6,13,15). The PutA protein is, in fact, bifunctional, possessing both proline oxidase and repressor activities (6).…”

Section: Methodsmentioning

confidence: 99%

“…There are other examples of membrane-associated regulatory proteins, such as ToxR from Vibrio cholerae, PutA from S. typhimurium, and BglS from E. coli (6,13,15). The PutA protein is, in fact, bifunctional, possessing both proline oxidase and repressor activities (6). More like the NadR system, the BglS protein is proposed to be a negative regulator of the bgl operon as well as a component of the P-glucoside phosphoenolpyruvatedependent phosphotransferase transport system (13).…”

Section: Methodsmentioning

confidence: 99%

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Regulation of NAD metabolism in Salmonella typhimurium: molecular sequence analysis of the bifunctional nadR regulator and the nadA-pnuC operon

et al. 1990

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In Salmonella typhimurium, de novo synthesis of NAD is regulated through the transcriptional control of the nadA and nadB loci. Likewise, the pyridine nucleotide salvage pathway is controlled at pncB. The transcriptional expression of these three loci is coordinately regulated by the product of nadR. However, there is genetic evidence suggesting that NadR is bifunctional, serving in both regulatory and transport capacities. One class of mutations in the nadR locus imparts a transport-defective PnuA-phenotype. These mutants retain regulation properties but are unable to transport nicotinamide mononucleotide (NMN) intact across the cell membrane. Other nadR mutants lose both regulatory and transport capabilities, while a third class loses only regulatory ability. The unusual NMN transport activity requires both the PnuC and NadR proteins, with the pnuC locus residing in an operon with nadA. To prove that nadlR encoded a single protein and to gain insight into a regulatory target locus, the nadR and nadA pnuC loci were cloned and sequenced. A DNA fragment which complemented both regulatory and transport mutations was found to contain a single open reading frame capable of encoding a 409-amino-acid protein (47,022 daltons), indicating that NadR is indeed bifunctional. Confirmation of the operon arrangement for nadA and pnuC was obtained through the sequence analysis of a 2.4-kilobase DNA fragment which complemented both NadA and PnuC mutant phenotypes. The nadA product, confirmed in maxicells, was a 365-amino-acid protein (40,759 daltons), while pnuC encoded a 322-amino-acid protein (36,930 daltons). The extremely hydrophobic (71%) nature of the PnuC protein indicated that it was an integral membrane protein, consistent with its central role in the transport of NMN across the cytoplasmic membrane. The results presented here and in previous studies suggest a hypothetical model in which NadR interacts with PnuC at low internal NAD levels, permitting transport of NMN intact into the cell. As NAD levels increase within the cell, the affinity of NadR for the operator regions of nadA, nadB, and pncB increases, repressing the transcription of these target genes.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Regulation of NAD metabolism in Salmonella typhimurium: molecular sequence analysis of the bifunctional nadR regulator and the nadA-pnuC operon

et al. 1990

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“…Supplementation with 5-aminolevulinic acid hydrochloride (ALA; Sigma Chemical Co.) was at 200 ng/ml (1.2 FM) in minimal medium and 20 Lg/ml (120 FM) in rich medium. Antibiotics were added to final concentrations in rich medium as follows: sodium ampicillin, 30 pg/ml; chloramphenicol, 20 [Lg/ml; kanamycin sulfate, 50 1Lg/ml; and tetracycline hydrochloride, 20 p.g/ml. Defined amino acid mix lacking methionine was made as a 200-fold-concentrated stock and added to minimal medium as described previously (48).…”

mentioning

confidence: 99%

Cloning, genetic characterization, and nucleotide sequence of the hemA-prfA operon of Salmonella typhimurium

Elliott

1989

J Bacteriol

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The first step in heme biosynthesis is the formation of 5-aminolevulinic acid (ALA). Mutations in two genes, hemA and hemL, result in auxotrophy for ALA in Salmonella typhimurium, but the roles played by these genes and the mechanism of ALA synthesis are not understood. I have cloned and sequenced the S. typhimurium hemA gene. The predicted polypeptide sequence for the HemA protein shows no similarity to known ALA synthases, and no ALA synthase activity was detected in extracts prepared from strains carrying the cloned hemA gene. Genetic analysis, DNA sequencing of amber mutations, and maxicell studies proved that the open reading frame identified in the DNA sequence encodes HemA. Another surprising finding of this study is that hemA lies directly upstream of prfA, which encodes peptide chain release factor 1 (RF-1). A hemA::Kan insertion mutation, constructed in vitro, was transferred to the chromosome and used to show that these two genes form an operon. The hemA gene ends with an amber codon, recognized by RF-1. I suggest a model for autogenous control of prfA expression by translation reinitiation.

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“…This system illustrates the direct interaction between a regulatory protein and flavin cofactors. An example of a flavoenzyme with both enzyme activity and repressor function is provided by the regulation of proline utilization in E. coli and Salmonella typhimurium (19)(20)(21). These bacteria are able to use proline as carbon and nitrogen sources.…”

Section: Flavins (Vitamin B2) Prokaryotesmentioning

confidence: 99%

Regulation of Gene Expression by Cofactors Derived from B Vitamins.

Brandsch

1994

Journal of Nutritional Science and Vitaminology, J Nutr Sci Vit

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SummaryVitamins represent precursor molecules for the majority of cofactors essential for various enzyme activities. Is the expression of proteins that require a specific cofactor for their function correlated to its availability? Examples are presented and discussed of the involvement of vitamin-derived cofactors in the regulatory mechanisms controlling gene expression in bacteria and eukaryotes at the transcriptional and trans lational level.

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Regulation of proline utilization in Salmonella typhimurium: Molecular characterization of the put operon, and DNA sequence of the put control region

Cited by 39 publications

References 40 publications

Regulation of NAD metabolism in Salmonella typhimurium: molecular sequence analysis of the bifunctional nadR regulator and the nadA-pnuC operon

Regulation of NAD metabolism in Salmonella typhimurium: molecular sequence analysis of the bifunctional nadR regulator and the nadA-pnuC operon

Cloning, genetic characterization, and nucleotide sequence of the hemA-prfA operon of Salmonella typhimurium

Regulation of Gene Expression by Cofactors Derived from B Vitamins.

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