Effect of nitrous oxide inactivation of vitamin B12-dependent methionine synthetase on the subcellular distribution of folate coenzymes in rat liver

Horne, Donald W.; Patterson, D; Cook, Robert

doi:10.1016/0003-9861(89)90556-0

Cited by 107 publications

(70 citation statements)

References 19 publications

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“…Preliminary studies indicated that nuclear and mitochondrial DNA were similarly labeled by [2-14 C]glycine, implying that either or both 5,10-CH 2 -THF and thymidine/thymidylate are able to pass out of the mitochondrion. In rodent liver mitochondria, one-carbon THF derivatives are trapped inside by polyglutamylation (49,50), but the 14 C label in thymidylate (or thymidine) can be exported to the cytosol/nucleus (40). Importantly, incorporation was greatly decreased in the gcvP Ϫ mutant and was partially restored after re-expression of the GCVP in the mutant background.…”

Section: Discussionmentioning

confidence: 99%

The Role of the Mitochondrial Glycine Cleavage Complex in the Metabolism and Virulence of the Protozoan Parasite Leishmania major

Scott

Hickerson

Vickers

et al. 2008

Journal of Biological Chemistry

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For the human pathogen Leishmania major, a key metabolic function is the synthesis of thymidylate, which requires 5,10-methylenetetrahydrofolate (5,10-CH 2 -THF). 5,10-CH 2 -THF can be synthesized from glycine by the mitochondrial glycine cleavage complex (GCC). Bioinformatic analysis revealed the four subunits of the GCC in the L. major genome, and the role of the GCC in parasite metabolism and virulence was assessed through studies of the P subunit (glycine decarboxylase (GCVP)). First, a tagged GCVP protein was expressed and localized to the parasite mitochondrion. Second, a gcvP ؊ mutant was generated and shown to lack significant GCC activity using an indirect in vivo assay after incorporation of label from [2-14 C]glycine into DNA. The gcvP ؊ mutant grew poorly in the presence of excess glycine or minimal serine; these studies also established that L. major promastigotes require serine for optimal growth. Although gcvP ؊ promastigotes and amastigotes showed normal virulence in macrophage infections in vitro, both forms of the parasite showed substantially delayed replication and lesion pathology in infections of both genetically susceptible or resistant mice. These data suggest that, as the physiology of the infection site changes during the course of infection, so do the metabolic constraints on parasite replication. This conclusion has great significance to the interpretation of metabolic requirements for virulence. Last, these studies call attention in trypanosomatid protozoa to the key metabolic intermediate 5,10-CH 2 -THF, situated at the junction of serine, glycine, and thymidylate metabolism. Notably, genome-based predictions suggest the related parasite Trypanosoma brucei is totally dependent on the GCC for 5,10-CH 2 -THF synthesis.

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Section: Discussionmentioning

confidence: 99%

The Role of the Mitochondrial Glycine Cleavage Complex in the Metabolism and Virulence of the Protozoan Parasite Leishmania major

Scott

Hickerson

Vickers

et al. 2008

Journal of Biological Chemistry

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“…The doses of MTX (400 μg/kg, i.p.) and nitrous oxide (80% N2O-20% O2; 4-hour exposure 3 days prior to the injury, then 2-hour exposures every other day for 2 weeks) were selected from a literature review (45)(46)(47)(48) and preliminary confirmatory experiments in our laboratory.…”

Section: Figure 10mentioning

confidence: 99%

Folate regulation of axonal regeneration in the rodent central nervous system through DNA methylation

Iskandar¹,

Rizk²,

Meier³

et al. 2010

J. Clin. Invest.

147

119

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The folate pathway plays a crucial role in the regeneration and repair of the adult CNS after injury. Here, we have shown in rodents that such repair occurs at least in part through DNA methylation. In animals with combined spinal cord and sciatic nerve injury, folate-mediated CNS axon regeneration was found to depend on injury-related induction of the high-affinity folate receptor 1 (Folr1). The activity of folate was dependent on its activation by the enzyme dihydrofolate reductase (Dhfr) and a functional methylation cycle. The effect of folate on the regeneration of afferent spinal neurons was biphasic and dose dependent and correlated closely over its dose range with global and gene-specific DNA methylation and with expression of both the folate receptor Folr1 and the de novo DNA methyltransferases. These data implicate an epigenetic mechanism in CNS repair. Folic acid and possibly other nontoxic dietary methyl donors may therefore be useful in clinical interventions to promote brain and spinal cord healing. If indeed the benefit of folate is mediated by epigenetic mechanisms that promote endogenous axonal regeneration, this provides possible avenues for new pharmacologic approaches to treating CNS injuries.

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“…analysis of reaction products Reaction mixtures were filtered through Centricon microconcentrators (10,um pore; Amicon) to separate enzyme from the reaction products. Reaction products were analysed by the modified method of Horne et al [12] using an Ultrasphere IP C-18 column (4.6 mm x 150 mm, 5-,um-diam. particles; Beckman) and a Spectra-Physics SP8700 solvent delivery system.…”

Section: Analysis Of Kinetic Datamentioning

confidence: 99%

Recombinant 10-formyltetrahydrofolate dehydrogenase catalyses both dehydrogenase and hydrolase reactions utilizing the synthetic substrate 10-formyl-5,8-dideazafolate

Krupenko

Wagner

Cook

1995

Biochemical Journal

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10-Formyltetrahydrofolate dehydrogenase (EC 1.5.1.6) is a bifunctional enzyme, displaying both NADP(+)-dependent dehydrogenase activity for the formation of tetrahydrofolate and CO2, and NADP(+)-independent hydrolase activity for the formation of tetrahydrofolate and formate. A previous report [Case, Kaisaki and Steele (1988) J. Biol. Chem. 263, 1024-1027] claimed that dehydrogenase and hydrolase activities were products of separate cytosolic and mitochondrial forms of this enzyme. Here we report that recombinant 10-formyltetrahydrofolate dehydrogenase carries out both enzymic reactions, proving that a product of a single gene, i.e. one protein, not two, has both activities. The stable synthetic analogue 10-formyl-5,8-dideazafolate can substitute for the labile natural substrate, 10-formyltetrahydrofolate, in both reactions. This was shown with both native and recombinant rat liver enzyme. The Km values for 10-formyl-5,8-dideazafolate were half of those for 10-formyltetrahydrofolate in both the dehydrogenase and hydrolytic reactions. The Vmax, values were similar for both substrates. Both dehydrogenase and hydrolase reactions were dependent on the presence of 2-mercaptoethanol. The pH optima were 7.8 and 5.6 for the dehydrogenase and hydrolase reactions respectively, consistent with the presence of two active sites in the enzyme.

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Effect of nitrous oxide inactivation of vitamin B12-dependent methionine synthetase on the subcellular distribution of folate coenzymes in rat liver

Cited by 107 publications

References 19 publications

The Role of the Mitochondrial Glycine Cleavage Complex in the Metabolism and Virulence of the Protozoan Parasite Leishmania major

The Role of the Mitochondrial Glycine Cleavage Complex in the Metabolism and Virulence of the Protozoan Parasite Leishmania major

Folate regulation of axonal regeneration in the rodent central nervous system through DNA methylation

Recombinant 10-formyltetrahydrofolate dehydrogenase catalyses both dehydrogenase and hydrolase reactions utilizing the synthetic substrate 10-formyl-5,8-dideazafolate

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