Effect of ascorbate on oxygen uptake and growth of <i>Escherichia coli</i> B

Richter, Holly E.; Switala, Jacek; Loewen, P.C.

doi:10.1139/m88-140

Cited by 13 publications

(11 citation statements)

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“…SgaT proved not to be homologous to any functionally characterized protein. Two possibilities were considered: (i) SgaT-SgaB-SgaA could be a novel type of enzyme II complex, or (ii) SgaT could be a secondary transporter, while SgaA and SgaB might regulate expression of the sga operon or the activity of one or more of its gene products (18,25).It has been known for over 60 years that various bacteria, including E. coli, can ferment L-ascorbate (L-xyloascorbate [vitamin C]) under anaerobic but not aerobic conditions (7,19,32). The unstable hydrolysis product of L-ascorbate, 3-keto-Lgulonate, has been implicated as an intermediate in its catabolism (28).…”

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“…It has been known for over 60 years that various bacteria, including E. coli, can ferment L-ascorbate (L-xyloascorbate [vitamin C]) under anaerobic but not aerobic conditions (7,19,32). The unstable hydrolysis product of L-ascorbate, 3-keto-Lgulonate, has been implicated as an intermediate in its catabolism (28).…”

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confidence: 99%

“…The unstable hydrolysis product of L-ascorbate, 3-keto-Lgulonate, has been implicated as an intermediate in its catabolism (28). The dissimilation of L-ascorbate, both during coculture with other carbon sources and as a sole carbon source, has been documented for E. coli (19,31). In animal tissues, the principal route of L-ascorbate metabolism involves enzymatic and nonenzymatic oxidation to dehydroascorbate, an unstable lactone that hydrolyzes spontaneously to 2,3-di-keto-L-gulonate (9).…”

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The Ascorbate Transporter of Escherichia coli

et al. 2003

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The sgaTBA genes of Escherichia coli encode a putative 12-transmembrane ␣-helical segment (12 TMS) transporter, an enzyme IIB-like protein and an enzyme IIA-like protein of the phosphotransferase system (PTS), respectively. We show that all three proteins as well as the energy-coupling PTS proteins, enzyme I and HPr, are required for the anaerobic utilization and uptake of L-ascorbate in vivo and its phosphoenolpyruvatedependent phosphorylation in vitro. The transporter exhibits an apparent K m for L-ascorbate of 9 M and is highly specific. The sgaTBA genes are regulated at the transcriptional level by the yjfQ gene product, as well as by Crp and Fnr. The yjfR gene product is essential for L-ascorbate utilization and probably encodes a cytoplasmic L-ascorbate 6-phosphate lactonase. We conclude that SgaT represents a novel prototypical enzyme IIC that functions with SgaA and SgaB to allow phosphoryl transfer from HPr(his-P) to L-ascorbate via the phosphoryl transfer pathway: PEP ¡ enzyme I-P ¡ HPr-P ¡ IIA-PIn 1996, we reported computational analyses of three operons present in the Escherichia coli genome that appeared to encode enzymes and a transporter concerned with sugar metabolism (18). These operons, sga, sgb, and sgc, encode enzymes homologous to pentose-phosphate 3-and 4-epimerases, and sga and sgc also encode homologues of constituents of the bacterial phosphotransferase system (PTS) (22). The sga operon includes two genes, sgaA and sgaB, that encode homologues of fructose/mannitol enzymes IIA and lactose/N,NЈ-diacetylchitobiose enzymes IIB, respectively ( Fig. 1). No IIC homologue was identified, but upstream of the sgaB and sgaA genes is a gene, sgaT, that encodes a membrane protein with 12 putative transmembrane helical segments, a characteristic of many secondary carriers (25). SgaT proved not to be homologous to any functionally characterized protein. Two possibilities were considered: (i) SgaT-SgaB-SgaA could be a novel type of enzyme II complex, or (ii) SgaT could be a secondary transporter, while SgaA and SgaB might regulate expression of the sga operon or the activity of one or more of its gene products (18,25).It has been known for over 60 years that various bacteria, including E. coli, can ferment L-ascorbate (L-xyloascorbate [vitamin C]) under anaerobic but not aerobic conditions (7,19,32). The unstable hydrolysis product of L-ascorbate, 3-keto-Lgulonate, has been implicated as an intermediate in its catabolism (28). The dissimilation of L-ascorbate, both during coculture with other carbon sources and as a sole carbon source, has been documented for E. coli (19,31). In animal tissues, the principal route of L-ascorbate metabolism involves enzymatic and nonenzymatic oxidation to dehydroascorbate, an unstable lactone that hydrolyzes spontaneously to 2,3-di-keto-L-gulonate (9).Recently, Yew and Gerlt (31) showed that the anaerobic utilization of L-ascorbate is dependent on three enzymes encoded downstream of sgaTBA within the sga operon (Fig. 1). These enzymes catalyze the conversion of the phosp...

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The Ascorbate Transporter of Escherichia coli

et al. 2003

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“…This is consistent with results obtained by other investigators. Richter et al (1988) reported that addition of ascorbate to aerobically growing cultures of E. coli B caused only a short pause in growth, and no subsequent change in the rate of growth. Tabak et al (2003) reported that 10-20 mg/ ml ascorbic acid inhibited Helicobacter pylori growth under microaerophilic conditions.…”

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confidence: 99%

Effects of ascorbic acid, citric acid, lactic acid, NaCl, potassium sorbate and Thymus vulgaris extract on Staphylococcus aureus and Escherichia coli

Abu-Ghazaleh¹

2013

Afr. J. Microbiol. Res.

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Staphylococcus aureus and some strains of Escherichia coli are frequently implicated in foodborne diseases. This study examined the effects of some compounds (ascorbic acid, citric acid, lactic acid, sodium chloride, potassium sorbate and Thymus vulgaris extract) on growth of S. aureus and E. coli. Lactic acid (0.03% or 0.1%) alone nearly completely inhibited growth of S. aureus or E. coli, respectively. Citric acid (0.03%) reduced growth and ascorbic acid (0.1%) nearly completely inhibited the growth of S. aureus; the percentages of inhibition after 24 h incubation in nutrient broth were 33 and 91%, respectively. Citric acid (0.03%) and ascorbic acid (0.1%) did not inhibit growth of E. coli, but a lag occurred before increase in number could be observed. NaCl (5%) significantly reduced growth of both strains; the percentages of inhibition of S. aureus and E. coli after 24 h incubation were 55 and 64%, respectively. Thymus vulgaris extract (0.3%) alone or potassium sorbate (0.09%) alone reduced growth of both strains. A combination of citric acid (0.03%) and potassium sorbate (0.05%) or citric acid (0.03%) and NaCl (5%) nearly completely or completely inhibited, respectively, the growth of S. aureus. For E. coli, combination of citric acid (0.03%) and potassium sorbate (0.05%) together completely inhibited the growth. A combination of citric acid (0.03%) and NaCl (3%) or T. vulgaris extract (0.3%) and NaCl (3%) greatly reduced the growth of E. coli strains and the percentages of inhibition after 24 h incubation were 65 and 70%, respectively.

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“…Based on computational docking of the L-xylulose 5-phosphate substrate to UlaE and structural similarities of the active site of this enzyme to the active sites of other epimerases, a metal-dependent epimerization mechanism for UlaE is proposed, and Glu155 and Glu251 are implicated as catalytic residues. Mutation and activity measurements for structurally equivalent residues in related epimerases supported this mechanistic proposal.It has been known for nearly 70 years that various bacteria, including Escherichia coli, can ferment L-ascorbate (vitamin C) under anaerobic conditions (2,10,30,40). This process has been demonstrated to involve proteins encoded by two divergently transcribed operons, the ulaGR and ulaABCDEF operons (3,40,44).…”

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Structure of l -Xylulose-5-Phosphate 3-Epimerase (UlaE) from the Anaerobic l -Ascorbate Utilization Pathway of Escherichia coli : Identification of a Novel Phosphate Binding Motif within a TIM Barrel Fold

et al. 2008

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Three catabolic enzymes, UlaD, UlaE, and UlaF, are involved in a pathway leading to fermentation of L-ascorbate under anaerobic conditions. UlaD catalyzes a ␤-keto acid decarboxylation reaction to produce L-xylulose-5-phosphate, which undergoes successive epimerization reactions with UlaE (L-xylulose-5-phosphate 3-epimerase) and UlaF (L-ribulose-5-phosphate 4-epimerase), yielding D-xylulose-5-phosphate, an intermediate in the pentose phosphate pathway. We describe here crystallographic studies of UlaE from Escherichia coli O157:H7 that complete the structural characterization of this pathway. UlaE has a triosephosphate isomerase (TIM) barrel fold and forms dimers. The active site is located at the C-terminal ends of the parallel ␤-strands. The enzyme binds Zn 2؉ , which is coordinated by Glu155, Asp185, His211, and Glu251. We identified a phosphate-binding site formed by residues from the ␤1/␣1 loop and ␣3 helix in the N-terminal region. This site differs from the well-characterized phosphate-binding motif found in several TIM barrel superfamilies that is located at strands ␤7 and ␤8. The intrinsic flexibility of the active site region is reflected by two different conformations of loops forming part of the substrate-binding site. Based on computational docking of the L-xylulose 5-phosphate substrate to UlaE and structural similarities of the active site of this enzyme to the active sites of other epimerases, a metal-dependent epimerization mechanism for UlaE is proposed, and Glu155 and Glu251 are implicated as catalytic residues. Mutation and activity measurements for structurally equivalent residues in related epimerases supported this mechanistic proposal.It has been known for nearly 70 years that various bacteria, including Escherichia coli, can ferment L-ascorbate (vitamin C) under anaerobic conditions (2,10,30,40). This process has been demonstrated to involve proteins encoded by two divergently transcribed operons, the ulaGR and ulaABCDEF operons (3,40,44). The ulaG gene encodes L-ascorbate-6-phosphate lactonase. The ulaABCDEF operon encodes an L-ascorbate phosphotransferase transport system (UlaABC, formerly designated SgaTBA) responsible for the uptake and phosphorylation of L-ascorbate, and the ulaDEF genes encode three enzymes that catalyze the conversion of the phosphorylated, hydrolytic product of L-ascorbate, 3-keto-L-gulonate-6-phosphate, to D-xylulose-5-phosphate, which is subsequently metabolized by the pentose phosphate pathway. UlaD (formerly SgaH) decarboxylates 3-keto-L-gulonate-6-phosphate, yielding L-xylulose-5-phosphate, which is subsequently epimerized by UlaE (formerly SgaU) at C-3 to L-ribulose-5-phosphate and then epimerized by UlaF (formerly SgaE) at C-4 to D-xylulose-5-phosphate (Fig.

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Effect of ascorbate on oxygen uptake and growth of Escherichia coli B

Cited by 13 publications

References 7 publications

The Ascorbate Transporter of Escherichia coli

The Ascorbate Transporter of Escherichia coli

Effects of ascorbic acid, citric acid, lactic acid, NaCl, potassium sorbate and Thymus vulgaris extract on Staphylococcus aureus and Escherichia coli

Structure of l -Xylulose-5-Phosphate 3-Epimerase (UlaE) from the Anaerobic l -Ascorbate Utilization Pathway of Escherichia coli : Identification of a Novel Phosphate Binding Motif within a TIM Barrel Fold

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