Hydroxypyruvate Reductase Activity in Paracoccus denitrificans

Bamforth, Charles W.; Quayle, J. R.

doi:10.1099/00221287-101-2-259

Cited by 17 publications

(4 citation statements)

References 23 publications

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“…Studies of potential effectors did not reveal any physiologically significant activators or inhibitors of the enzyme studied here. Some substrate inhibition was observed, as described earlier for the enzymes from P. denitrificans (3) and Chlamydomonas reinhardtii (6), and mild product inhibition was observed, as shown for H. methylovorum GM2 (7). However, for the reduction reaction, none of these effects are strong at physiologically significant concentrations.…”

Section: Discussionmentioning

confidence: 89%

Purification and characterization of hydroxypyruvate reductase from the facultative methylotroph Methylobacterium extorquens AM1

Chistoserdova

Lidstrom

1991

J Bacteriol

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Hydroxypyruvate reductase was purified to homogeneity from the facultative methylotroph Methylobacterium extorquens AM1. It has a molecular mass of about 71 kDa, and it consists of two identical subunits with a molecular mass of about 37 kDa. This enzyme uses both NADH (Km = 0.04 mM) and NADPH (Km = 0.06 mM) as cofactors, uses hydroxypyruvate (Km = 0.1 mM) and glyoxylate (Km = 1.5 mM) as the only substrates for the forward reaction, and carries out the reverse reaction with glycerate (Km = 2.6 mM) only. It was not possible to detect the conversion of glycolate to glyoxylate, a proposed role for this enzyme. Kinetics and inhibitory studies of the enzyme from M. extorquens AM1 suggest that hydroxypyruvate reductase is not a site for regulation of the serine cycle at the level of enzyme activity.Methylobacterium extorquens AM1 is a gram-negative facultative methylotroph capable of growth on methanol, methylamine, and a variety of multicarbon compounds which assimilates C1 units via the serine cycle during growth on C1 substrates (12,17). A number of enzymes have been shown to be specifically involved in dissimilation and assimilation of C1 substrates in M. extorquens AM1, and these are known to be inducible by growth on the appropriate C1 substrates. In addition, the assimilatory enzymes are repressed by the presence of multicarbon compounds such as succinate or glucose, but the dissimilatory enzymes are not (2,14).Although intensive work on the methanol oxidation system in M. extorquens AM1 is beginning to shed light on both the biochemistry and the regulatory mechanisms involved (1,13,15,16,18), the serine cycle is less well understood. This cycle functions by the condensation of methylene tetrahydrofolate and glycine to generate serine, conversion of serine to phosphoenolpyruvate via several steps, and carboxylation of phosphoenolpyruvate to generate oxaloacetate. The oxaloacetate is then converted to malyl coenzyme A (CoA), which is cleaved to acetyl-CoA and glyoxylate. The acetyl-CoA is oxidized to glyoxylate, and this is then converted to the acceptor molecule, glycine. However, the route of acetyl-CoA oxidation in this last stage is unknown. Isocitrate lyase is not present in this organism, and a novel, as yet undetermined pathway must carry out this oxidation (2).Hydroxypyruvate reductase catalyzes the reduction of hydroxypyruvate to glycerate, one of the key steps in the conversion of serine to phosphoenolpyruvate in the serine cycle. It has also been suggested to carry out the reduction of glyoxylate to glycolate in cell extracts, but the significance of this reaction in vivo is not known (2, 4). Mutants in hydroxypyruvate reductase would be expected to be defective in growth on C1 compounds, but should grow normally on other compounds. However, mutant 20BL, which lacks hydroxypyruvate reductase, is unable to grow on both C1 and C2 compounds (4). This suggests a second role for * Corresponding author.hydroxypyruvate reductase involving C2 compounds, most likely, the oxidation of glycolate to glyoxylate (4...

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Section: Discussionmentioning

confidence: 89%

Purification and characterization of hydroxypyruvate reductase from the facultative methylotroph Methylobacterium extorquens AM1

Chistoserdova

Lidstrom

1991

J Bacteriol

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“…This enzyme has previously been observed in a number of autotrophic and methylotrophic bacteria that do not use the serine pathway (Bamforth & Quayle, 1977;Taylor, 1977) and is thought to be involved in the assimilation of phosphoglycollate generated by the ribulose bisphosphate oxygenase activity of ribulose bisphosphate carboxylase (Colby et al, 1979;Taylor et al, 1981). The various pathways for glycollate metabolism in autotrophs have been discussed by Beudeker et al, (1981).…”

Section: Enzyme Activitiesmentioning

confidence: 91%

Isolation, Characterization and Autotrophic Metabolism of a Moderately Thermophilic Carboxydobacterium, Pseudomonas thermocarboxydovorans sp. nov.

et al. 1984

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Three strains of Gram-negative, obligately aerobic, moderately thermophilic, CO-utilizing bacteria have been isolated by enrichment at 45-55 "C in mineral medium under CO, H2 and air. The properties of the strains, designated C2, S1 and FE, suggest that they should be included in a single species that we have named Pseudomonas thermocarboxydovorans. The isolates can grow on CO and a limited range of organic and amino acids; neither sugars nor H2/C02 support growth and €I2 is not oxidized. Strain C2 contains a soluble, inducible C0:phenazine ethosulphate oxidoreductase, lacks hydrogenase and assimilates CO via ribulose bisphosphate carboxylase. The organism apparently contains a mechanism for assimilating phosphoglycollate. Pseudomonas carboxydovorans, P . carboxydoflava, P . carboxydohydrogena, P . gazotropha,Cornomonas compransoris and Achromobacter carboxydus, can utilize CO as sole carbon and energy source (Kim & Hegeman, 1983;Meyer & Schlegel, 1983). These bacteria are Gramnegative, mostly mesophilic and, with the exception of A . carboxydus, able to grow autotrophically with hydrogen (H,) and carbon dioxide (CO,). This paper describes the isolation, characterization and growth of three strains of a novel thermophilic species of carboxydobacterium.Abbreviations: API 20E, API ZYM and API 5OCH refer to the bacteriological test strips supplied by API Laboratory Products, Grafton Way, Basingstoke, Hants, UK ; PES, phenazine ethosulphate; PHB, poly-Qhydroxybutyrate; DCPIP, 2,6-dichlorophenolindophenol.

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“…It should be noted that hydroxypyruvate reduction can be catalysed by glyoxylate reductase (Bamforth & Quayle, 1977). Extracts of T. neapolitanus were also able to convert glycerate into pyruvate when ATP, Mg2+, PEP and pyruvate kinase were added to the assay system, which is an indication of glycerate kinase activity.…”

Section: R E S U L T Smentioning

confidence: 98%

Glycollate Metabolism in the Obligate Chemolithotroph Thiobacillus neapolitanus Grown in Continuous Culture

1981

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Hydroxypyruvate Reductase Activity in Paracoccus denitrificans

Cited by 17 publications

References 23 publications

Purification and characterization of hydroxypyruvate reductase from the facultative methylotroph Methylobacterium extorquens AM1

Purification and characterization of hydroxypyruvate reductase from the facultative methylotroph Methylobacterium extorquens AM1

Isolation, Characterization and Autotrophic Metabolism of a Moderately Thermophilic Carboxydobacterium, Pseudomonas thermocarboxydovorans sp. nov.

Glycollate Metabolism in the Obligate Chemolithotroph Thiobacillus neapolitanus Grown in Continuous Culture

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