Acetylation of N-terminal valine of glycine N-methyltransferase affects enzyme inhibition by folate

Luka, Zigmund; Loukachevitch, Lioudmila V.; Wagner, Conrad

doi:10.1016/j.bbapap.2008.04.016

Cited by 13 publications

(19 citation statements)

References 30 publications

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“…(6S)-5-CH 3 -H 4 PteGlu 1 was a gift from EPROVA (Switzerland). To prepare natural (6S)-5-CH 3 -H 4 PteGlu 5 the mixture of (6R/6S)-5-CH 3 -H 4 PteGlu 5 purchased from Schircks Laboratories (Switzerland) was separated by binding to GNMT, removal of non-bound folate (presumably the 6R-form) by using Spin-Columns and release of free folate by heating the GNMT-folate complex at +80 °C in presence of 60 mM β-mercaptoethanol as was done in [6]. …”

Section: Methodsmentioning

confidence: 99%

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Differences in folate–protein interactions result in differing inhibition of native rat liver and recombinant glycine N-methyltransferase by 5-methyltetrahydrofolate

Luka

Pakhomova

Loukachevitch

et al. 2012

Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics

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Glycine N-methyltransferase (GNMT) is a key regulatory enzyme in methyl group metabolism. In mammalian liver it reduces S-adenosylmethionine levels by using it to methylate glycine, producing N-methylglycine (sarcosine) and S-adenosylhomocysteine. GNMT is inhibited by binding two molecules of 5-methyltetrahydrofolate (mono- or polyglutamate forms) per tetramer of the active enzyme. Inhibition is sensitive to the status of the N-terminal valine of GNMT and to polyglutamation of the folate inhibitor. It is inhibited by pentaglutamate form more efficiently compared to monoglutamate form. The native rat liver GNMT contains an acetylated N-terminal valine and is inhibited much more efficiently compared to the recombinant protein expressed in E. coli where the N-terminus is not acetylated. In this work we used a protein crystallography approach to evaluate the structural basis for these differences. We show that in the folate-GNMT complexes with the native enzyme, two folate molecules establish three and four hydrogen bonds with the protein. In the folate-recombinant GNMT complex only one hydrogen bond is established. This difference results in more effective inhibition by folate of the native liver GNMT activity compared to the recombinant enzyme.

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Section: Methodsmentioning

confidence: 99%

“…Moreover, inhibition of the native enzyme is much more efficient compared to recombinant enzyme by both forms of folate [6]. …”

Section: Introductionmentioning

confidence: 99%

Differences in folate–protein interactions result in differing inhibition of native rat liver and recombinant glycine N-methyltransferase by 5-methyltetrahydrofolate

Luka

Pakhomova

Loukachevitch

et al. 2012

Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics

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“…The bound folate is thought to impede the swinging out of position of the N termini that normally allows access of the substrates to the active sites. Despite similar binding constants, folate inhibition of the liver enzyme with its acetylated N-terminal valines is much stronger than inhibition of the enzyme expressed in E. coli, in which valine is not acetylated; 50% inhibition is seen at 0.0013 and 0.59 mM 5-CH 3 -H 4 PteGlu 5 for the native and recombinant enzymes, respectively (30). Fig.…”

Section: Inhibition Of Gnmt By Folatementioning

confidence: 99%

Glycine N-Methyltransferase and Regulation of S-Adenosylmethionine Levels

Luka

Mudd

Wagner

2009

Journal of Biological Chemistry

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Methylation is a major biological process. It has been shown to be important in formation of compounds such as phosphatidylcholine, creatine, and many others and also participates in epigenetic effects through methylation of histones and DNA. The donor of methyl groups for almost all cellular methylation reactions is S-adenosylmethionine. It seems that the level of S-adenosylmethionine must be regulated in response to developmental stages and metabolic changes, and the enzyme glycine N-methyltransferase has been shown to play a major role in such regulation in mammals. This minireview will focus on the latest discoveries in the elucidation of the mechanism of that regulation. Discovery of S-Adenosylmethionine and Its VersatilityAdoMet 2 was discovered in 1951 by Cantoni as the "active methionine" used in the enzymatic transfer of the methyl group of methionine to nicotinamide to form N 1 -methylnicotinamide (1). With the exception of a few intracellular parasites that take up AdoMet from their hosts, AdoMet is formed from ATP and methionine by methionine adenosyltransferases present in all (or virtually all) cells of all organisms, including archaea, eubacteria, and eukaryotes. The reaction involves, initially, transfer of the adenosyl group of ATP to methionine, with the remainder of the ATP being converted to enzyme-bound tripolyphosphate. The latter compound is hydrolyzed to pyrophosphate and phosphate, which are then released (2). Being a sulfonium compound, AdoMet provides the large amounts of free energy (20 ϳkcal/mol) needed for methyl group transfers.AdoMet is possibly the most (or, compared with ATP, the second most) versatile compound in Nature. It is a source not only of methyl groups but, in diverse reactions in various organisms, provides methylene groups, four-carbon moieties, ribosyl groups, amino groups, and, after decarboxylation, threecarbon moieties for polyamines and ethylene (3). It may be converted to a 5Ј-deoxyadenosyl free radical that participates in a great variety of "radical SAM" reactions (4). AdoMet also functions as a regulator of many metabolic pathways in mammals, plants, and bacteria.In mammals, Ͼ90% of AdoMet is used for methylation reactions by at least 50 different methyltransferases (5). Methylation of both small molecules (e.g. phosphatidylethanolamine and guanidinoacetate) and macromolecules (DNA, RNA, histones, and other proteins) plays critical roles in cellular metabolism. Methylations of DNA and histones are major events in epigenetics. Therefore, the level of AdoMet must be carefully regulated to maintain cellular homeostasis. Recent evidence has established that GNMT plays a major role in maintaining normal AdoMet levels in mammals. GNMT Genes and ProteinsIn 1960, enzymatically catalyzed direct transfer of a methyl group from AdoMet to glycine (forming sarcosine) was demonstrated. The activity was found in liver extracts from guinea pig, rat, rabbit, and mouse, but the enzyme was not purified until 1972 when Heady and Kerr, upon finding that glycine was a better acce...

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“…GNMT, a liver metabolic enzyme, in the hippocampus, where it was found to regulate intracellular levels of SAMe (the universal methyl donor in almost all methylation reactions) and therefore plays a very important role in DNA methylation (Rowling and Schalinske 2003) and is also a tumor suppressor gene. GNMT affects genetic stability by regulating the ratio of S-adenosylmethionine (SAM) to Sadenosylhomocysteine and serves as a folate-binding protein, which binds environmental carcinogens such as benzo(a)pyrene and aflatoxin B1 (Luka et al 2007) to prevent DNA adduct formation and carcinogen-induced cytotoxicity (Luka et al 2008). Accumulating evidence suggests that GNMT also plays a critical role in regulating immune responses by modulating CD4+ T cell proliferation through the mTOR signaling pathway .…”

Section: Discussionmentioning

confidence: 99%

Proteomics analysis of liver tissues from C57BL/6J mice receiving low-dose 137Cs radiation

Liang

Yin

et al. 2015

Environ Sci Pollut Res

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Differentially expressed proteins in liver tissues of C57BL/6J mice receiving low-dose (137)Cs radiation were examined by proteomics analysis. Compared with the control group, 80 proteins were differentially expressed in the irradiated group. Among the 40 randomly selected proteins used for peptide mass fingerprinting analysis and bioinformatics, 24 were meaningful. These proteins were related to antioxidant defense, amino acid metabolism, detoxification, anti-tumor development, amino acid transport, anti-peroxidation, and composition of respiratory chain. Western blot analysis showed that catalase (CAT), glycine N-methyltransferase (GNMT), and glutathione S-transferase P1 (GSTP1) were up-regulated in the irradiated group; these results were in agreement with qPCR results. These results show that CAT, GNMT, and GSTP1 may be related to stress response induced by low-dose irradiation in mice liver. The underlying mechanism however requires further investigation.

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Acetylation of N-terminal valine of glycine N-methyltransferase affects enzyme inhibition by folate

Cited by 13 publications

References 30 publications

Differences in folate–protein interactions result in differing inhibition of native rat liver and recombinant glycine N-methyltransferase by 5-methyltetrahydrofolate

Differences in folate–protein interactions result in differing inhibition of native rat liver and recombinant glycine N-methyltransferase by 5-methyltetrahydrofolate

Glycine N-Methyltransferase and Regulation of S-Adenosylmethionine Levels

Proteomics analysis of liver tissues from C57BL/6J mice receiving low-dose 137Cs radiation

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