Stimulation of rat kidney, spleen and brain DNA-(cytosine-5)-methyltransferases by divalent cobalt ions

Pfohl‐Leszkowicz, Annie; Baldacini, Olivier; Keith, Gérard; Dirheimer, G.

doi:10.1016/0300-9084(87)90151-9

Cited by 8 publications

(4 citation statements)

References 21 publications

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“…These data suggest that 4-O-methylation of GlcA proceeds via a catalytic mechanism characteristic of plant class I cation-dependent OMTs (23), consistent with an early report using a particulate enzyme from corn cobs (24 (39). Although several cobalt-dependent mammalian DNA N-methyltransferases have been described (40), GXMT1 is the only Co 2+ -dependent OMT described to date.…”

Section: Resultssupporting

confidence: 69%

4- O -methylation of glucuronic acid in Arabidopsis glucuronoxylan is catalyzed by a domain of unknown function family 579 protein

Urbanowicz

Peña

Ratnaparkhe

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

160

144

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The hemicellulose 4-O-methyl glucuronoxylan is one of the principle components present in the secondary cell walls of eudicotyledonous plants. However, the biochemical mechanisms leading to the formation of this polysaccharide and the effects of modulating its structure on the physical properties of the cell wall are poorly understood. We have identified and functionally characterized an Arabidopsis glucuronoxylan methyltransferase (GXMT) that catalyzes 4-O-methylation of the glucuronic acid substituents of this polysaccharide. AtGXMT1, which was previously classified as a domain of unknown function (DUF) 579 protein, specifically transfers the methyl group from S-adenosyl-L-methionine to O-4 of α-D-glucopyranosyluronic acid residues that are linked to O-2 of the xylan backbone. Biochemical characterization of the recombinant enzyme indicates that GXMT1 is localized in the Golgi apparatus and requires Co 2+ for optimal activity in vitro. Plants lacking GXMT1 synthesize glucuronoxylan in which the degree of 4-O-methylation is reduced by 75%. This result is correlated to a change in lignin monomer composition and an increase in glucuronoxylan release during hydrothermal treatment of secondary cell walls. We propose that the DUF579 proteins constitute a previously undescribed family of cation-dependent, polysaccharide-specific O-methyl-transferases. This knowledge provides new opportunities to selectively manipulate polysaccharide O-methylation and extends the portfolio of structural targets that can be modified either alone or in combination to modulate biopolymer interactions in the plant cell wall.recalcitrance | biosynthesis

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Section: Resultssupporting

confidence: 69%

4- O -methylation of glucuronic acid in Arabidopsis glucuronoxylan is catalyzed by a domain of unknown function family 579 protein

Urbanowicz

Peña

Ratnaparkhe

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

160

144

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“…The above results, together with earlier results(Pfohl-Leszkowicz et al, 1987), suggest the existence of two different DNA methylases or the occurrence of different conformations of thefigure 10: Detection of methylated nucleotides. An autoradiogram is shown of a developed TLC plate to which 0.16 Mg of 32P-postlabeled…”

supporting

confidence: 75%

“…Nevertheless, the DNA methylase is able to transfer methyl groups to unmethylated sites in a de novo reaction. Since we have previously found that DNA methylase activities are stimulated by cobalt ions (Pfohl-Leszkowicz et al, 1987), we thought that several natural compounds that contain cobalt, such as cobalamin derivatives, could also have an action in these two enzymatic DNA methylation reactions.…”

mentioning

confidence: 99%

Effect of cobalamin derivatives on in vitro enzymic DNA methylation: methylcobalamin can act as a methyl donor

Pfohl‐Leszkowicz

Keith²,

Dirheimer³

1991

Biochemistry

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5-Methylcytosine synthesis in DNA involves the transfer of methyl groups from S-adenosyl-methionine to the 5'-position of cytosine through the action of DNA (cytosine-5)-methyltransferase. The rate of this reaction has been found to be enhanced by cobalt ions. We therefore analyzed the influence of vitamin B12 and related compounds containing cobalt on DNA methylation. Vitamin B12, methylcobalamin, and coenzyme B12 were found to enhance significantly the de novo DNA methylation in the presence of S-adenosylmethionine for concentrations up to 1 microM, but at higher concentrations these compounds were found to inhibit DNA methylation. Methylcobalamin behaves as a competitive inhibitor of the enzymatic methylation reaction (Ki = 15 microM), the Km for S-adenosylmethionine being 8 microM. In addition, the use of radioactive methylcobalamin shows that it can be used as a methyl donor in the de novo and maintenance DNA methylation reactions. Thus, two DNA methylation pathways could exist: one involving methylation from S-adenosylmethionine and a second one involving methylation from methylcobalamin.

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“…Hix and Augusto [62] showed that DNA becomes highly methylated when attacked by large numbers of methyl radicals induced by iron ions. e results obtained by Pfohl-Leszkowicz et al [63] also showed that heavy metal ions can significantly inhibit methyltransferase activities, and such heavy metal ions as Pb, Cu, and Zn have the ability to inhibit 5-methyltransferase activities. Also, Rossiello et al [64] found that excessive exposure to Pb can result in low methylation of DNA.…”

Section: Genetic Mutations and Variationsmentioning

confidence: 86%

Progress in the Research of the Toxicity Effect Mechanisms of Heavy Metals on Freshwater Organisms and Their Water Quality Criteria in China

Hong

Liao

Yan

et al. 2020

Journal of Chemistry

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Water quality criteria are the scientific basis for formulating water quality standards and environmental management practices. Due to the development of urbanization and industrialization, the problem of heavy metal pollution has become a serious environmental problem. Heavy metals not only have major impacts on aquatic organisms, but also seriously threaten human health. However, the current environmental criteria refer to the maximum value limitations of environmental factors in environmental media where harmful or detrimental effects are not produced on specific protected objects. This study reviewed the sources, hazard levels, toxic effect mechanisms, and the current research status of China’s water quality criteria for heavy metal pollutants. In addition, the focus and direction of future research on the toxic effects of heavy metal on aquatic organisms and the necessary criteria changes were discussed. The present study would provide an important theoretical basis for the future research of water quality criteria and risk assessment of heavy metal pollutants.

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Stimulation of rat kidney, spleen and brain DNA-(cytosine-5)-methyltransferases by divalent cobalt ions

Cited by 8 publications

References 21 publications

4- O -methylation of glucuronic acid in Arabidopsis glucuronoxylan is catalyzed by a domain of unknown function family 579 protein

4- O -methylation of glucuronic acid in Arabidopsis glucuronoxylan is catalyzed by a domain of unknown function family 579 protein

Effect of cobalamin derivatives on in vitro enzymic DNA methylation: methylcobalamin can act as a methyl donor

Progress in the Research of the Toxicity Effect Mechanisms of Heavy Metals on Freshwater Organisms and Their Water Quality Criteria in China

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