Role of the MetR regulatory system in vitamin B12-mediated repression of the Salmonella typhimurium metE gene

Wu, Whei-Fen; Urbanowski, Mark L.; Stauffer, George V.

doi:10.1128/jb.174.14.4833-4837.1992

Cited by 25 publications

(15 citation statements)

References 22 publications

(24 reference statements)

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“…The MetR protein acts as an activator for the transcription of metE, metA, metF, and metH (93). Homocysteine functions as a coregulator for MetR-mediated regulation and has a positive effect on the expression of metE, which encodes a transmethylase, and metF, which encodes 5,10-methylenetetrahydrofolate reductase but has a negative effect on metA and metH.…”

Section: Discussionmentioning

confidence: 99%

Salmonella enterica Serovar Typhimurium Colonizing the Lumen of the Chicken Intestine Grows Slowly and Upregulates a Unique Set of Virulence and Metabolism Genes

Harvey¹,

Watson²,

Hulme

et al. 2011

Infect Immun

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The pattern of global gene expression in Salmonella enterica serovar Typhimurium bacteria harvested from the chicken intestinal lumen (cecum) was compared with that of a late-log-phase LB broth culture using a whole-genome microarray. Levels of transcription, translation, and cell division in vivo were lower than those in vitro. S. Typhimurium appeared to be using carbon sources, such as propionate, 1,2-propanediol, and ethanolamine, in addition to melibiose and ascorbate, the latter possibly transformed to D-xylulose. Amino acid starvation appeared to be a factor during colonization. Bacteria in the lumen were non-or weakly motile and nonchemotactic but showed upregulation of a number of fimbrial and Salmonella pathogenicity island 3 (SPI-3) and 5 genes, suggesting a close physical association with the host during colonization. S. Typhimurium bacteria harvested from the cecal mucosa showed an expression profile similar to that of bacteria from the intestinal lumen, except that levels of transcription, translation, and cell division were higher and glucose may also have been used as a carbon source.

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Section: Discussionmentioning

confidence: 99%

Salmonella enterica Serovar Typhimurium Colonizing the Lumen of the Chicken Intestine Grows Slowly and Upregulates a Unique Set of Virulence and Metabolism Genes

Harvey¹,

Watson²,

Hulme

et al. 2011

Infect Immun

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“…Thus, dual control of metE by both MetR and MetJ allows its transcription to be reduced under N-and S-limiting conditions. In addition to these proposed rationales, the MetR subcircuit is known to mediate decreased expression of metE when vitamin B12 is available and the more efficient MetH enzyme can function (30,32,37).…”

Section: Motilitymentioning

confidence: 99%

Lessons from Escherichia coli genes similarly regulated in response to nitrogen and sulfur limitation

Gyaneshwar

Paliy

McAuliffe

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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We previously characterized nutrient-specific transcriptional changes in Escherichia coli upon limitation of nitrogen (N) or sulfur (S). These global homeostatic responses presumably minimize the slowing of growth under a particular condition. Here, we characterize responses to slow growth per se that are not nutrientspecific. The latter help to coordinate the slowing of growth, and in the case of down-regulated genes, to conserve scarce N or S for other purposes. Three effects were particularly striking. First, although many genes under control of the stationary phase sigma factor RpoS were induced and were apparently required under S-limiting conditions, one or more was inhibitory under N-limiting conditions, or RpoS itself was inhibitory. RpoS was, however, universally required during nutrient downshifts. Second, limitation for N and S greatly decreased expression of genes required for synthesis of flagella and chemotaxis, and the motility of E. coli was decreased. Finally, unlike the response of all other met genes, transcription of metE was decreased under S-and N-limiting conditions. The metE product, a methionine synthase, is one of the most abundant proteins in E. coli grown aerobically in minimal medium. Responses of metE to S and N limitation pointed to an interesting physiological rationale for the regulatory subcircuit controlled by the methionine activator MetR.Escherichia coli genomics ͉ flagella ͉ methionine regulation ͉ nutrient metabolism ͉ RpoS W e have previously explored global responses of Escherichia coli K12 to limitation for the nutrients nitrogen (N) or sulfur (S) on glass-slide DNA microarrays (1). To determine responses of a wild-type strain, we compared its transcriptional profiles under nutrient-limiting and -excess conditions and under conditions of rapid transition between the two, magnifying transcriptional responses (2). Homeostatic responses to N or S limitation entail increased assimilation of preferred N or S sources, respectively, and scavenging of alternative N or S sources from the medium (1, 3). Common responses to N and S limitation apparently occur as a consequence of slow growth. Here, we characterize the latter responses, both increases and decreases in transcription, and explore several of them biologically. Materials and Methods BacterialStrains. An rpoS::Tn10 allele (4) and a Tn10 insertion at an innocuous locus (zih-102::Tn10) were transferred to NCM3722 by P1-mediated transduction to generate NCM3890 and control strain NCM3964, respectively. The same lesions were also transferred to MG1655 (CGSC 6300) [also known as NCM3105 (5)] to generate NCM3962 and NCM3963, respectively. NCM3876 [glnL(Up)] has been described (1), and NCM4022 was isolated as a spontaneous motile derivative of NCM3722 on an arginine swim plate. Nutrient Shifts and Other Growth Experiments.For carbon (C) and N downshift experiments growth of rpoS and control strains was monitored at 37°C in N Ϫ C Ϫ minimal medium containing various C or N sources. For C downshift experiments, ammonium chloride (1...

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“…Homocysteine may modulate the regulator role of MetR and is required for the metE gene activation (47). Furthermore, vitamin B 12 is involved in metE repression, probably by depletion of the coactivator homocysteine (53).…”

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confidence: 99%

Regulation of themetC-cysKOperon, Involved in Sulfur Metabolism inLactococcus lactis

et al. 2002

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Sulfur metabolism in gram-positive bacteria is poorly characterized. Information on the molecular mechanisms of regulation of genes involved in sulfur metabolism is limited, and no regulator genes have been identified. Here we describe the regulation of the lactococcal metC-cysK operon, encoding a cystathionine ␤-lyase (metC) and cysteine synthase (cysK). Its expression was shown to be negatively affected by high concentrations of cysteine, methionine, and glutathione in the culture medium, while sulfur limitation resulted in a high level of expression. Other sulfur sources tested showed no significant effect on metC-cysK gene expression. In addition we found that O-acetyl-L-serine, the substrate of cysteine synthase, was an inducer of the metC-cysK operon. Using a random mutagenesis approach, we identified two genes, cmbR and cmbT, involved in regulation of metC-cysK expression. The cmbT gene is predicted to encode a transport protein, but its precise role in regulation remains unclear. Disruption of cmbT resulted in a two-to threefold reduction of metC-cysK transcription. A 5.7-kb region containing the cmbR gene was cloned and sequenced. The encoded CmbR protein is homologous to the LysR family of regulator proteins and is an activator of the metC-cysK operon. In analogy to CysB from Escherichia coli, we propose that CmbR requires acetylserine to be able to bind the activation sites and subsequently activate transcription of the metC-cysK operon.

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Role of the MetR regulatory system in vitamin B12-mediated repression of the Salmonella typhimurium metE gene

Cited by 25 publications

References 22 publications

Salmonella enterica Serovar Typhimurium Colonizing the Lumen of the Chicken Intestine Grows Slowly and Upregulates a Unique Set of Virulence and Metabolism Genes

Salmonella enterica Serovar Typhimurium Colonizing the Lumen of the Chicken Intestine Grows Slowly and Upregulates a Unique Set of Virulence and Metabolism Genes

Lessons from Escherichia coli genes similarly regulated in response to nitrogen and sulfur limitation

Regulation of themetC-cysKOperon, Involved in Sulfur Metabolism inLactococcus lactis

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