Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.1.1.37 (DNA methyltransferase)
 4,983 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Four analogs of the natural cofactor S-adenosylmethionine (AdoMet) were tested for their ability to bind and inhibit the prokaryotic enzyme, EcoRI adenine DNA methylase. The EcoRI methylase transfers the methyl group from AdoMet to the second adenine in the double-stranded DNA sequence 5'GAATTC3'. Dissociation constants (KD) of the binary methylase-analog complexes obtained in the absence of DNA with S-adenosylhomocysteine (AdoHcy), sinefungin, N-methyl-AdoMet, and N-ethylAdoMet are 225, 43, greater than 1000, and greater than 1000 microM, respectively. In the presence of a DNA substrate, all four analogs show simple competitive inhibition with respect to AdoMet. The product of the enzymic reaction, AdoHcy, is a poor inhibitor of the enzyme (KI(AdoHcy) = 9 microM; KM(AdoMet) = 0.60 microM). Two synthetic analogs, N-methyl-AdoMet and N-ethyl-AdoMet, were also shown to be poor inhibitors with KI values of 50 and greater than 1000 microM, respectively. In contrast, the naturally occurring analog sinefungin was shown to be a highly potent inhibitor (KI = 10 nM). Gel retardation assays confirm that the methylase-DNA-sinefungin complex is sequence-specific. The ternary complex is the first sequence-specific complex detected for any DNA methylase. Potential applications to structural studies of methylase-DNA interactions are discussed.
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PMID:Inhibition of EcoRI DNA methylase with cofactor analogs. 234 14

The crystal structures of the binary complexes of the DNA methyltransferase M.TaqI with the inhibitor Sinefungin and the reaction product S-adenosyl-L-homocysteine were determined, both at 2.6 A resolution. Structural comparison of these binary complexes with the complex formed by M.TaqI and the cofactor S-adenosyl-L-methionine suggests that the key element for molecular recognition of these ligands is the binding of their adenosine part in a pocket, and discrimination between cofactor, reaction product and inhibitor is mediated by different conformations of these molecules; the methionine part of S-adenosyl-L-methionine is located in the binding cleft, whereas the amino acid moieties of Sinefungin and S-adenosyl-L-homocysteine are in a different orientation and interact with the active site amino acid residues 105NPPY108. Dissociation constants for the complexes of M.TaqI with the three ligands were determined spectrofluorometrically. Sinefungin binds more strongly than S-adenosyl-L-homocysteine or S-adenosyl-L-methionine, with KD=0.34 microM, 2.4 microM and 2.0 microM, respectively.
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PMID:Differential binding of S-adenosylmethionine S-adenosylhomocysteine and Sinefungin to the adenine-specific DNA methyltransferase M.TaqI. 899 24

Eukaryotic centromeres contain the kinetochore, which connects chromosomes to the spindle allowing segregation. During meiosis, centromeres are suppressed for inter-homolog crossover, as recombination in these regions can cause chromosome missegregation and aneuploidy. Plant centromeres are surrounded by transposon-dense pericentromeric heterochromatin that is epigenetically silenced by histone 3 lysine 9 dimethylation (H3K9me2), and DNA methylation in CG and non-CG sequence contexts. However, the role of these chromatin modifications in control of meiotic recombination in the pericentromeres is not fully understood. Here, we show that disruption of Arabidopsis thaliana H3K9me2 and non-CG DNA methylation pathways, for example, via mutation of the H3K9 methyltransferase genes KYP/SUVH4 SUVH5 SUVH6, or the CHG DNA methyltransferase gene CMT3, increases meiotic recombination in proximity to the centromeres. Using immunocytological detection of MLH1 foci and genotyping by sequencing of recombinant plants, we observe that H3K9me2 and non-CG DNA methylation pathway mutants show increased pericentromeric crossovers. Increased pericentromeric recombination in H3K9me2/non-CG mutants occurs in hybrid and inbred backgrounds and likely involves contributions from both the interfering and noninterfering crossover repair pathways. We also show that meiotic DNA double-strand breaks (DSBs) increase in H3K9me2/non-CG mutants within the pericentromeres, via purification and sequencing of SPO11-1-oligonucleotides. Therefore, H3K9me2 and non-CG DNA methylation exert a repressive effect on both meiotic DSB and crossover formation in plant pericentromeric heterochromatin. Our results may account for selection of enhancer trap Dissociation (Ds) transposons into the CMT3 gene by recombination with proximal transposon launch-pads.
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PMID:Epigenetic activation of meiotic recombination near Arabidopsis thaliana centromeres via loss of H3K9me2 and non-CG DNA methylation. 2953 Sep 27