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

A recent report in this journal [Vairapandi, M. and Duker, N.J. (1993) Nucleic Acids Res. 21, 5323-5327) presented evidence of an activity in HeLa cell nuclear extracts that released radiolabeled material from a poly(dG.dC) polymer that had been methylated and simultaneously labeled on cytosine residues by incubation with a CpG-specific DNA methylase and [methyl-3H]S-adenosylmethionine. Based on chromatographic evidence that the released products were thymine and 5-methylcytosine and on f1p4olabeling data suggesting a concomitant increase in abasic sites, the authors concluded that the releasing activity was a 5-methylcytosine-specific glycosylase and that the solubilized 5-methylcytosine was converted to thymine by a nuclear deaminase. We have confirmed that HeLa nuclear extracts promote release of ethanol-soluble radioactivity from a methyl-labeled poly(dG-5-methyl-dC)polymer, but the products released were neither 5-methylcytosine nor thymine. Furthermore, free 5-methylcytosine was not deaminated by incubation with the nuclear extract. The labeled compound released initially from the polymer appeared to be 5-methyl-deoxycytidine monophosphate, which was converted to 5-methyl-deoxycytidine, thymidine monophosphate, and/or thymidine by further incubation with the nuclear extract. The activity responsible for the release, therefore, was a nuclease. Release of 32P-labeled nucleotides from a 32P-labeled poly(dG-dC) polymer suggested, furthermore, that the activity was not specific for methylated DNA.
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PMID:Enzymic removal of 5-methylcytosine from poly(dG-5-methyl-dC) by HeLa cell nuclear extracts is not by a DNA glycosylase. 778 19

Analysis of 94 kb of DNA, located between map positions 88 and 182 kb in the 330-kb chlorella virus PBCV-1 genome, revealed 195 open reading frames (ORFs) 65 codons or longer. One hundred and five of the 195 ORFs were considered major ORFs. Twenty-six of the 105 major ORFs resembled genes in the databases including three chitinases, a chitosanase, three serine/threonine protein kinases, two additional protein kinases, a tyrosine protein phosphatase, two ankyrins, an ornithine decarboxylase, a copper/zinc-superoxide dismutase, a proliferating cell nuclear antigen, a DNA polymerase, a fibronectin-binding protein, the yeast Ski2 protein, an adenine DNA methyltransferase and its corresponding DNA site-specific endonuclease, and an amidase. The genes for the 105 major ORFs were evenly distributed along the genome and, except for one noncoding 1788-nucleotide stretch, the genes were close together. Unexpectedly, a 900-bp region in the 1788-bp noncoding sequence resembled a CpG island.
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PMID:Analysis of 94 kb of the chlorella virus PBCV-1 330-kb genome: map positions 88 to 182. 861 77

Transformed cells can spontaneously silence genes by de novo methylation, and it is generally assumed that this is due to DNA methyltransferase activity. We have tested the alternative hypothesis that gene silencing could be due to the uptake of 5-methyl-dCMP into DNA, via the di- and triphosphonucleotides. 5-Methyl-dCMP would be present in cells from the ongoing repair of DNA. We have isolated a strain of Chinese hamster ovary (CHO) cells, designated HAM-, which spontaneously silences two tested genes at a very high frequency. We have shown that this strain incorporates 5-[3H]methyldeoxycytidine into 5-methylcytosine and thymine in DNA. It also has low 5-methyl-dCMP deaminase activity. Another HAM+ strain has high deaminase activity and a very low frequency of gene silencing. The starting strain, CHO K1, has a phenotype intermediate between HAM- and HAM+.
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PMID:Evidence for gene silencing by endogenous DNA methylation. 967 46

At the current time, genome sequences of a total of 13 Porphyromonas gingivalis strains are available, including five completed genomes (strains ATCC 33277, HG66, TDC60, JCVISC001, and W83) and eight high-coverage draft sequences (F0185, F0566, F0568, F0569, F0570, SJD2, W4087, and W50) that are assembled into fewer than 300 contigs. This study compared these genomes at both nucleotide and protein sequence levels in order to understand their phylogenetic and functional relatedness. There are four copies of 16S rRNA gene sequences in each of the strains of ATCC 33277, HG66, TDC60, and W83 and one copy in the other nine genomes. These 25 16S rRNA sequences represent only 13 unique sequences. The five copies in W83 and W50 are identical and the three copies in HG66 are identical to the four copies in ATCC 33277, suggesting close evolutionary lineage between W83 and W50, as well as HG66 and ATCC 33277. Genome-wide comparison based on "Rapid Annotation using Subsystem Technology" (RAST) also showed that for the overall biological functions of the genomes, W83 is closer to W50, and HG66 to ATCC33277, than to other genomes. The comparison of the RAST subsystems identified biological functions that are unique to individual, shared by some, or by all genomes. Functions unique to individual genomes include: a tetracycline resistance protein TetQ, DNA metabolism gene YcfH, and DNA repair gene exonuclease SbcC (only in SJD2); very-short-patch mismatch repair endonuclease and a phage packaging terminase similar to Bacteroides phage B124-14 (in W4087); an internalin similar to a Listeria surface virulence protein (W83); a Type I restriction-modification system (F0569); an iron acquisition/heme transport protein (F0566); colicin I receptor and carbamoylputrescine amidase (W50); L-serine dehydratase (TDC60); and spermidine synthase and ribokinase (JCVISC001). The results also identified biological functions that are missing in individual or several genomes. For example, JCVISC001 does not contain the CRISPR (clustered regularly interspaced short palindromic repeats) system - a prokaryotic immune system that confers resistance to foreign genetic elements such as plasmids and phages. Some genomes are enriched with multiple copies of certain genes [e.g., TDC60, W50, and W83 encode 2-4 copies of 4-alpha-glucanotransferase (amylomaltase in glycan metabolism)], while others only have a single copy in the genome. Complete results of this study will be presented and available online for download.
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PMID:Comparative genomics and proteomics of 13 Porphyromonas gingivalis strains. 2638 43