Human methylenetetrahydrofolate reductase plus SAM
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ABSTRACT:
SUBMITTER: Thomas James McCorvie
PROVIDER: EMPIAR-11926 | biostudies-other |
REPOSITORIES: biostudies-other
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Project description:Methylenetetrahydrofolate reductase (MTHFR) catalyzes the reduction of methylenetetrahydrofolate to methyltetrahydrofolate, the methyl donor for the conversion of homocysteine to methionine. Regulation of MTHFR activity is crucial for maintaining cellular concentrations of methionine and S-adenosylmethionine (AdoMet). Purified recombinant human MTHFR expressed in insect cells is multiply phosphorylated on an N-terminal extension of the protein that contains a highly conserved serine-rich region. Treatment by alkaline phosphatase removes seven phosphoryl groups from the enzyme. Thr-34 was identified as one of the seven phosphorylation sites by using a monoclonal antibody directed toward pThr-Pro. Mutation of Thr-34 to Ala completely blocks modification as judged by mass spectrometric analysis, suggesting that Thr-34 is the priming phosphorylation site. The Thr34Ala mutant was expressed in baculovirus-infected insect cells, and its enzymic properties were compared with wild-type enzyme. The mutant enzyme and alkaline phosphatase-treated wild-type enzyme are more active than untreated wild-type enzyme and less sensitive to inhibition by saturating AdoMet, indicating that phosphorylation at Thr-34 is critical for allosteric regulation of human MTHFR activity by AdoMet. The absence of methionine and the presence of adenosine in the cell culture medium, which lead to a low intracellular AdoMet/S-adenosylhomocysteine ratio, are associated with faster electrophoretic mobility of MTHFR, presumably because of less or no phosphorylation. Because the faster-mobility MTHFR is associated with the more active form of MTHFR, this response is likely to increase methionine production. Those observations suggest that AdoMet functions not only as an allosteric inhibitor but also to control phosphorylation of human MTHFR.
| S-EPMC1180802 | biostudies-literature
Project description:Methylenetetrahydrofolate reductase (MTHFR) catalyzes the conversion of methylenetetrahydrofolate to methyltetrahydrofolate, the major methyl donor for the conversion of homocysteine to methionine. Two common polymorphisms of the human enzyme have been identified: 677C>T, which leads to the substitution of Ala-222 by valine, and 1298A>C, which leads to the replacement of Glu-429 by alanine; the former polymorphism is the most frequent genetic cause of mild hyperhomocysteinemia, a risk factor for cardiovascular disease. By using a baculovirus expression system, recombinant human MTHFR has been expressed at high levels and purified to homogeneity in quantities suitable for biochemical characterization. The Glu429Ala protein has biochemical properties that are indistinguishable from the wild-type enzyme. The Ala222Val MTHFR, however, has an enhanced propensity to dissociate into monomers and to lose its FAD cofactor on dilution; the resulting loss of activity is slowed in the presence of methyltetrahydrofolate or adenosylmethionine. This biochemical phenotype is in good agreement with predictions made on the basis of studies comparing wild-type Escherichia coli MTHFR with a mutant, Ala177Val, homologous to the Ala222Val mutant human enzyme [Guenther, B. D., et al. (1999) Nat. Struct. Biol. 6, 359-365].
| S-EPMC64948 | biostudies-literature
Project description:Methylenetetrahydrofolate reductase (MTHFR) catalyzes the irreversible conversion of 5,10-methylene-tetrahydrofolate (THF) to 5-methyl-THF, thereby committing one-carbon units to the methionine cycle. While MTHFR has long been known to be allosterically inhibited by S-adenosylmethionine (SAM), only relatively recently has N-terminal multisite phosphorylation been shown to provide an additional layer of regulation. In vitro, the multiply phosphorylated form of MTHFR is more sensitive to allosteric inhibition by SAM. Here we sought to investigate the kinases responsible for MTHFR multisite phosphorylation and the physiological function of MTHFR phosphorylation in cells. We identified DYRK1A/2 and GSK3A/B among the kinases that phosphorylate MTHFR. In addition, we found that MTHFR phosphorylation is maintained by adequate cellular SAM levels, which are sensed through the C-terminal SAM binding domain of MTHFR. To understand the function of MTHFR phosphorylation in cells, we generated MTHFR CRISPR knockin mutant lines that effectively abolished MTHFR phosphorylation and compared them with the parental cell lines. Whereas the parental cell lines showed increased 5-methyl-THF production in response to homocysteine treatment, the knockin cell lines had high basal levels of 5-methyl-THF and did not respond to homocysteine treatment. Overall, our results suggest that MTHFR multisite phosphorylation coordinates with SAM binding to inhibit MTHFR activity in cells.
| S-EPMC6414673 | biostudies-literature
Project description:5,10-methylenetetrahydrofolate reductase (MTHFR) commits folate-derived one-carbon units to generate the methyl-donor S-adenosyl-L-methionine (SAM). Eukaryotic MTHFR appends to the well-conserved catalytic domain (CD) a unique regulatory domain (RD) that confers feedback inhibition by SAM. Here we determine the cryo-electron microscopy structures of human MTHFR bound to SAM and its demethylated product S-adenosyl-L-homocysteine (SAH). In the active state, with the RD bound to a single SAH, the CD is flexible and exposes its active site for catalysis. However, in the inhibited state the RD pocket is remodelled, exposing a second SAM-binding site that was previously occluded. Dual-SAM bound MTHFR demonstrates a substantially rearranged inter-domain linker that reorients the CD, inserts a loop into the active site, positions Tyr404 to bind the cofactor FAD, and blocks substrate access. Our data therefore explain the long-distance regulatory mechanism of MTHFR inhibition, underpinned by the transition between dual-SAM and single-SAH binding in response to cellular methylation status.
| S-EPMC11018872 | biostudies-literature
Project description:Major depressive disorder (MDD) is a disorder that carries significant psychosocial and economic implications. Research efforts have focused on identifying biomarkers that can aid in the prediction, diagnosis, and efficacious treatment of MDD. Most of this focus has been placed on a polymorphism of the methylenetetrahydrofolate reductase (MTHFR) gene, C677T. MTHFR C677T is screened during MDD diagnosis in many protocols. However, MTHFR C667T poses conflicting data in various ethnic groups and geographic populations calling into question its utility. Another polymorphism, MTHFR A1298C, has often taken the back-seat to MTHFR C677T in respect to research focus. MTHFR A1298C is implicated in irregular homocysteine metabolism and aberrant folate cycles and, through this, it may play a role as either a driver in the development of MDD or as a predictive or diagnostic marker, possibly in combination with C677T. The number of studies evaluating MTHFR A1298C and the power of those studies is lacking and thus larger studies are required to confirm the association between this polymorphism and MDD.
| S-EPMC5711500 | biostudies-literature
Project description:5-Methyltetrahydrofolate, the major form of folate in plasma, is a carbon donor for the remethylation of homocysteine to methionine. This form of folate is generated from 5,10-methylenetetrahydrofolate through the action of 5,10-methylenetetrahydrofolate reductase (MTHFR), a cytosolic flavoprotein. Patients with an autosomal recessive severe deficiency of MTHFR have homocystinuria and a wide range of neurological and vascular disturbances. We have recently described the isolation of a cDNA for MTHFR and the identification of two mutations in patients with severe MTHFR deficiency. We report here the characterization of seven novel mutations in this gene: six missense mutations and a 5' splice-site defect that activates a cryptic splice site in the coding sequence. We also present a preliminary analysis of the relationship between genotype and phenotype for all nine mutations identified thus far in this gene. A nonsense mutation and two missense mutations (proline to leucine and threonine to methionine) in the homozygous state are associated with extremely low activity (0%-3%) and onset of symptoms within the 1st year of age. Other missense mutations (arginine to cysteine and arginine to glutamine) are associated with higher enzyme activity and later onset of symptoms.
| S-EPMC1801446 | biostudies-other
Project description:Background and objectiveMethylenetetrahydrofolate reductase (MTHFR) is a key enzyme involved in folate metabolism and one-carbon metabolism. MTHFR gene polymorphism affects enzyme activity. MTHFR gene polymorphism is closely related to many human diseases, such as cardiocerebrovascular diseases, diabetes, neural tube defects (NTDs), tumors, and so on. In the field of Andrology, MTHFR gene polymorphism may be associated with male infertility and erectile dysfunction (ED), and there is a possibility of treating male infertility and ED by supplementing with folic acid. However, its exact pathophysiologic mechanism is not fully understood. We sought to obtain a robust understanding of the interactions between MTHFR gene polymorphism, oxidative stress, DNA methylation, hyperhomocysteinemia (HHcy), male infertility, and ED.MethodsWe performed a non-systematic literature review using the PubMed database to identify articles specifically related to MTHFR, male infertility and ED.Key content and findingsOur literature review on MTHFR gene polymorphism in male infertility patients indicates a significant association between C677T gene polymorphism and male infertility. There is limited literature on the correlation between ED and MTHFR gene polymorphism, and there are two different conclusions, related and unrelated. More clinical data are needed to clarify the conclusion. There is a possibility of using folic acid supplementation to treat male infertility and ED, especially for patients with thymine-thymine (TT) genotype. Future research is necessary to further understand the relationship between MTHFR gene polymorphism and male infertility and ED.ConclusionsOur literature review on MTHFR gene polymorphism in male infertility patients indicates a significant association between C677T gene polymorphism and male infertility. Folic acid supplementation can improve sperm quality. The correlation between MTHFR gene polymorphisms and ED is questionable and needs to be confirmed by more clinical data. MTHFR gene polymorphisms are associated with homocysteine (Hcy) levels, which affects vascular endothelial function and may be related to the development of vascular ED (VED). Folic acid supplementation improves International Index for Erectile Function (IIEF) questionnaire scores in ED patients in whom phosphodiesterase 5 inhibitor (PDE5i) alone is ineffective.
| S-EPMC11399056 | biostudies-literature
Project description:Methylenetetrahydrofolate reductase deficiency; MTHFR (MIM 236250) is widely studied with more than 200 reported cases up to our knowledge from pediatrics to adult patients. Clinical presentation of MTHFR deficiency has a wide spectrum and its severity correlates with the degree of the enzyme activity. We report here seven pediatric cases with variable presentations including apnea at early infancy, in addition to hydrocephalus that needed drainage.
| S-EPMC7479436 | biostudies-literature
Project description:Moorella thermoacetica can grow with H₂ and CO₂, forming acetic acid from 2 CO₂ via the Wood-Ljungdahl pathway. All enzymes involved in this pathway have been characterized to date, except for methylenetetrahydrofolate reductase (MetF). We report here that the M. thermoacetica gene that putatively encodes this enzyme, metF, is part of a transcription unit also containing the genes hdrCBA, mvhD, and metV. MetF copurified with the other five proteins encoded in the unit in a hexaheteromeric complex with an apparent molecular mass in the 320-kDa range. The 40-fold-enriched preparation contained per mg protein 3.1 nmol flavin adenine dinucleotide (FAD), 3.4 nmol flavin mononucleotide (FMN), and 110 nmol iron, almost as predicted from the primary structure of the six subunits. It catalyzed the reduction of methylenetetrahydrofolate with reduced benzyl viologen but not with NAD(P)H in either the absence or presence of oxidized ferredoxin. It also catalyzed the reversible reduction of benzyl viologen with NADH (diaphorase activity). Heterologous expression of the metF gene in Escherichia coli revealed that the subunit MetF contains one FMN rather than FAD. MetF exhibited 70-fold-higher methylenetetrahydrofolate reductase activity with benzyl viologen when produced together with MetV, which in part shows sequence similarity to MetF. Heterologously produced HdrA contained 2 FADs and had NAD-specific diaphorase activity. Our results suggested that the physiological electron donor for methylenetetrahydrofolate reduction in M. thermoacetica is NADH and that the exergonic reduction of methylenetetrahydrofolate with NADH is coupled via flavin-based electron bifurcation with the endergonic reduction of an electron acceptor, whose identity remains unknown.
| S-EPMC4135698 | biostudies-literature
Project description:Folate metabolism has been associated with cancers via alterations in nucleotide synthesis, DNA methylation, and DNA repair. We hypothesized that genetic variants in methylenetetrahydrofolate reductase (MTHFR), a key enzyme of folate metabolism, would affect the prognosis of prostate cancer. Three haplotype-tagging single-nucleotide polymorphisms (SNPs) across the MTHFR gene region were genotyped in a cohort of 458 patients with clinically localized prostate cancer treated with radical prostatectomy. One SNP, rs9651118, was associated with disease recurrence, and the association persisted after multivariate analyses adjusting for known risk factors. Public dataset analyses suggested that rs9651118 affects MTHFR expression. Quantitative real-time polymerase chain reaction analysis revealed that MTHFR expression is significantly upregulated in prostate tumor tissues when compared with adjacent normal tissues. Furthermore, overexpression of MTHFR correlates with cancer recurrence and death in two independent publicly available prostate cancer datasets. In conclusion, our data provide rationale to further validate the clinical utility of MTHFR rs9651118 as a biomarker for prognosis in prostate cancer.
| S-EPMC5187796 | biostudies-literature