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Enzymes that catalyse CpG methylation in DNA, including the DNA methyltransferases 1 (DNMT1), 3A (DNMT3A) and 3B (DNMT3B), are indispensable for mammalian tissue development and homeostasis.sup.1-4. They are also implicated in human developmental disorders and cancers.sup.5-8, supporting the critical role of DNA methylation in the specification and maintenance of cell fate. Previous studies have suggested that post-translational modifications of histones are involved in specifying patterns of DNA methyltransferase localization and DNA methylation at promoters and actively transcribed gene bodies.sup.9-11. However, the mechanisms that control the establishment and maintenance of intergenic DNA methylation remain poorly understood. Tatton-Brown-Rahman syndrome (TBRS) is a childhood overgrowth disorder that is defined by germline mutations in DNMT3A. TBRS shares clinical features with Sotos syndrome (which is caused by haploinsufficiency of NSD1, a histone methyltransferase that catalyses the dimethylation of histone H3 at K36 (H3K36me2).sup.8,12,13), which suggests that there is a mechanistic link between these two diseases. Here we report that NSD1-mediated H3K36me2 is required for the recruitment of DNMT3A and maintenance of DNA methylation at intergenic regions. Genome-wide analysis shows that the binding and activity of DNMT3A colocalize with H3K36me2 at non-coding regions of euchromatin. Genetic ablation of Nsd1 and its paralogue Nsd2 in mouse cells results in a redistribution of DNMT3A to H3K36me3-modified gene bodies and a reduction in the methylation of intergenic DNA. Blood samples from patients with Sotos syndrome and NSD1-mutant tumours also exhibit hypomethylation of intergenic DNA. The PWWP domain of DNMT3A shows dual recognition of H3K36me2 and H3K36me3 in vitro, with a higher binding affinity towards H3K36me2 that is abrogated by TBRS-derived missense mutations. Together, our study reveals a trans-chromatin regulatory pathway that connects aberrant intergenic CpG methylation to human neoplastic and developmental overgrowth. H3K36me2 targets DNMT3A to intergenic regions and this process, together with H3K36me3-mediated recruitment of DNMT3B, has a key role in establishing and maintaining genomic DNA methylation landscapes., Author(s): Daniel N. Weinberg [sup.1] , Simon Papillon-Cavanagh [sup.2] , Haifen Chen [sup.2] , Yuan Yue [sup.3] , Xiao Chen [sup.4] [sup.5] , Kartik N. Rajagopalan [sup.6] , Cynthia Horth [...]

Methyltransferases of the mixed-lineage leukaemia (MLL) family--which include MLL1, MLL2, MLL3, MLL4, SET1A and SET1B--implement methylation of histone H3 on lysine 4 (H3K4), and have critical and distinct roles in the regulation of transcription in haematopoiesis, adipogenesis and development.sup.1-6. The C-terminal catalytic SET (Su(var.)3-9, enhancer of zeste and trithorax) domains of MLL proteins are associated with a common set of regulatory factors (WDR5, RBBP5, ASH2L and DPY30) to achieve specific activities.sup.7-9. Current knowledge of the regulation of MLL activity is limited to the catalysis of histone H3 peptides, and how H3K4 methyl marks are deposited on nucleosomes is poorly understood. H3K4 methylation is stimulated by mono-ubiquitination of histone H2B on lysine 120 (H2BK120ub1), a prevalent histone H2B mark that disrupts chromatin compaction and favours open chromatin structures, but the underlying mechanism remains unknown.sup.10-12. Here we report cryo-electron microscopy structures of human MLL1 and MLL3 catalytic modules associated with nucleosome core particles that contain H2BK120ub1 or unmodified H2BK120. These structures demonstrate that the MLL1 and MLL3 complexes both make extensive contacts with the histone-fold and DNA regions of the nucleosome; this allows ease of access to the histone H3 tail, which is essential for the efficient methylation of H3K4. The H2B-conjugated ubiquitin binds directly to RBBP5, orienting the association between MLL1 or MLL3 and the nucleosome. The MLL1 and MLL3 complexes display different structural organizations at the interface between the WDR5, RBBP5 and MLL1 (or the corresponding MLL3) subunits, which accounts for the opposite roles of WDR5 in regulating the activity of the two enzymes. These findings transform our understanding of the structural basis for the regulation of MLL activity at the nucleosome level, and highlight the pivotal role of nucleosome regulation in histone-tail modification. Cryo-electron microscopy structures of mixed-lineage leukaemia methyltransferases 1 and 3 associated with unmodified or mono-ubiquitinated nucleosome reveal the structural basis for the activity specificity and regulation of these enzymes., Author(s): Han Xue [sup.1] , Tonghui Yao [sup.1] , Mi Cao [sup.2] , Guanjun Zhu [sup.1] , Yan Li [sup.3] , Guiyong Yuan [sup.2] , Yong Chen [sup.1] , Ming [...]

SHARPIN, an adaptor for the linear ubiquitin chain assembly complex (LUBAC), plays important roles in NF-[kappa]B signaling and inflammation. Here, we have demonstrated a LUBAC-independent role for SHARPIN in regulating melanoma growth. We observed that SHARPIN interacted with PRMT5, a type II protein arginine methyltransferase, and increased its multiprotein complex and methyltransferase activity. Activated PRMT5 controlled the expression of the transcription factors SOX10 and MITF by SHARPIN-dependent arginine dimethylation and inhibition of the transcriptional corepressor SKI. Activation of PRMT5 by SHARPIN counteracted PRMT5 inhibition by methylthioadenosine, a substrate of methylthioadenosine phosphorylase, which is codeleted with cyclin-dependent kinase inhibitor 2A (CDKN2A) in approximately 15% of human cancers. Collectively, we identified a LUBAC-independent role for SHARPIN in enhancing PRMT5 activity that contributes to melanomagenesis through the SKI/SOX10 regulatory axis., Introduction Concerted regulation of posttranslational protein modification is central to the maintenance of cellular homeostasis, and not surprisingly, such modification is often deregulated in pathophysiological conditions, including cancer. Ubiquitination and [...]

Background: Bisphenol A (BPA), a ubiquitous environmental endocrine disruptor targeting estrogen receptors (ERs), has been implicated in the promotion of breast cancer. Perinatal exposure of BPA could induce longitudinal alteration of DNA hydroxymethylation in imprinted loci of mouse blood cells. To date, no data has been reported on the effects of BPA on DNA hydroxymethylation in breast cells. Therefore, we asked whether BPA can induce DNA hydroxymethylation change in human breast cells. Given that dysregulated epigenetic DNA hydroxymethylation is observed in various cancers, we wondered how DNA hydroxymethylation modulates cancer development, and specifically, whether and how BPA and its analogs promote breast cancer development via DNA hydroxymethylation. Objectives: We aimed to explore the interplay of the estrogenic activity of bisphenols at environmental exposure dose levels with TET dioxygenase-catalyzed DNA hydroxymethylation and to elucidate their roles in the proliferation of [ER.sup.+] breast cancer cells as stimulated by environmentally relevant bisphenols. Methods: Human MCF-7 and T47D cell lines were used as ER-dependent breast cell proliferation models, and the human MDA-MB-231 cell line was used as an ER-independent breast cell model. These cells were treated with BPA or bisphenol S (BPS) to examine BPA/BPS-related proliferation. Ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) and enzyme-linked immunosorbent assays (ELISAs) were used to detect DNA hydroxymethylation. Crispr/Cas9 and RNA interference technologies, quantitative polymerase chain reaction (qPCR), and Western blot analyses were used to evaluate the expression and function of genes. Co-immunoprecipitation (Co-IP), bisulfite sequencing-PCR (BSP), and chromatin immunoprecipitation-qPCR (ChIP-qPCR) were used to identify the interactions of target proteins. Results: We measured higher proliferation in ER+ breast cancer cells treated with BPA or its replacement, BPS, accompanied by an ER[alpha]-dependent decrease in genomic DNA hydroxymethylation. The results of our overexpression, knockout, knockdown, and inhibition experiments suggested that TET2-catalyzed DNA hydroxymethylation played a suppressive role in BPA/BPS-stimulated cell proliferation. On the other hand, we observed that TET2 was negatively regulated by the activation of ER[alpha] (dimerized and phosphorylated), which was also induced by BPA/BPS binding. Instead of a direct interaction between TET2 and ER[alpha], data of our Co-IP, BSP, and ChIP-qPCR experiments indicated that the activated ER[alpha] increased the DNA methyltransferase (DNMT)-mediated promoter methylation of TET2, leading to an inhibition of the TET2 expression and DNA hydroxymethylation. Conclusions: We identified a new feedback circuit of ER[alpha] activation-DNMT-TET2-DNA hydroxymethylation in [ER.sup.+] breast cancer cells and uncovered a pivotal role of TET2-mediated DNA hydroxymethylation in modulating BPA/BPS-stimulated proliferation. Moreover, to our knowledge, we for the first time established a linkage among chemical exposure, DNA hydroxymethylation, and tumor-associated proliferation. These findings further clarify the estrogenic activity of BPA/BPS and its profound implications for the regulation of epigenetic DNA hydroxymethylation and cell proliferation., Introduction Bisphenol A (BPA) is a well-known environmental endocrine disruptor, causing adverse alterations in the reproductive system, liver, and mammary glands (Vandenberg et al. 2007; Michalowicz 2014; Rodgers et al. [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.cell.2009.12.002 Byline: Jamy C. Peng (1), Anton Valouev (2), Tomek Swigut (1), Junmei Zhang (5), Yingming Zhao (6), Arend Sidow (2)(3), Joanna Wysocka (1)(4) Keywords: STEMCELL; DEVBIO; PROTEINS Abstract: Polycomb Repressive Complex 2 (PRC2) regulates key developmental genes in embryonic stem (ES) cells and during development. Here we show that Jarid2/Jumonji, a protein enriched in pluripotent cells and a founding member of the Jumonji C (JmjC) domain protein family, is a PRC2 subunit in ES cells. Genome-wide ChIP-seq analyses of Jarid2, Ezh2, and Suz12 binding reveal that Jarid2 and PRC2 occupy the same genomic regions. We further show that Jarid2 promotes PRC2 recruitment to the target genes while inhibiting PRC2 histone methyltransferase activity, suggesting that it acts as a 'molecular rheostat' that finely calibrates PRC2 functions at developmental genes. Using Xenopus laevis as a model we demonstrate that Jarid2 knockdown impairs the induction of gastrulation genes in blastula embryos and results in failure of differentiation. Our findings illuminate a mechanism of histone methylation regulation in pluripotent cells and during early cell-fate transitions. Author Affiliation: (1) Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA (2) Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA (3) Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA (4) Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305, USA (5) Protein Chemistry Technology Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA (6) Ben May Department for Cancer Research, University of Chicago, Chicago, IL 60637, USA Article History: Received 3 June 2009; Revised 17 August 2009; Accepted 1 December 2009 Article Note: (miscellaneous) Published: December 24, 2009

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2009.07.017 Byline: Ryan M. Anderson (a), Justin A. Bosch (a), Mary G. Goll (b), Daniel Hesselson (a), P. Duc Si Dong (a), Donghun Shin (a), Neil C. Chi (a)(c), Chong Hyun Shin (a), Amnon Schlegel (a)(d), Marnie Halpern (b), Didier Y.R. Stainier (a) Keywords: Methylation; Dnmt1; Pancreas; Epigenetics; Regeneration; Zebrafish; ENU mutagenesis; Mutant; Beta cells; Liver Abstract: Developmental mechanisms regulating gene expression and the stable acquisition of cell fate direct cytodifferentiation during organogenesis. Moreover, it is likely that such mechanisms could be exploited to repair or regenerate damaged organs. DNA methyltransferases (Dnmts) are enzymes critical for epigenetic regulation, and are used in concert with histone methylation and acetylation to regulate gene expression and maintain genomic integrity and chromosome structure. We carried out two forward genetic screens for regulators of endodermal organ development. In the first, we screened for altered morphology of developing digestive organs, while in the second we screed for the lack of terminally differentiated cell types in the pancreas and liver. From these screens, we identified two mutant alleles of zebrafish dnmt1. Both lesions are predicted to eliminate dnmt1 function; one is a missense mutation in the catalytic domain and the other is a nonsense mutation that eliminates the catalytic domain. In zebrafish dnmt1 mutants, the pancreas and liver form normally, but begin to degenerate after 84 h post fertilization (hpf). Acinar cells are nearly abolished through apoptosis by 100 hpf, though neither DNA replication, nor entry into mitosis is halted in the absence of detectable Dnmt1. However, endocrine cells and ducts are largely spared. Surprisingly, dnmt1 mutants and dnmt1 morpholino-injected larvae show increased capacity for pancreatic beta cell regeneration in an inducible model of pancreatic beta cell ablation. Thus, our data suggest that Dnmt1 is dispensable for pancreatic duct or endocrine cell formation, but not for acinar cell survival. In addition, Dnmt1 may influence the differentiation of pancreatic beta cell progenitors or the reprogramming of cells toward the pancreatic beta cell fate. Author Affiliation: (a) Department of Biochemistry and Biophysics, Programs in Developmental Biology, Genetics, and Human Genetics, Diabetes Center, and Liver Center, University of California, San Francisco, MC 2711 Rock Hall Room 384, 1550 Fourth Street, San Francisco, CA 94158-2324, USA (b) Department of Embryology, Carnegie Institution for Science 3520 San Martin Drive, Baltimore MD 21218, USA (c) Department of Medicine, University of California, San Francisco, 505 Parnassus Ave., San Francisco, CA 94143, USA (d) Department of Medicine, Division of Endocrinology, San Francisco General Hospital, 1001 Potrero Ave., San Francisco, CA 941110, USA Article History: Received 31 January 2009; Revised 7 July 2009; Accepted 15 July 2009

Di- and trimethylation of histone H4 lysine20 (H4K20) are thought to play an important role in controlling gene expression in vertebrates and in Drosophila. By inducing a null mutation in Drosophiht Suv4-20, we show that it encodes the histone H4 lysine20 di- and trimethyltransferase. In Suv4-20 mutants, the H4K20 di- and trimethyl marks are strongly reduced or absent, and the monomethyl mark is significantly increased. We find that even with this biochemical function, Suv4-20 is not required tot survival wad does not control position-effect variegation (PEV).

SET domain genes have been identified in numbers of bacterial genomes based on similarity to SET domains of eukaryotic histone methyltransferases. Herein, a Chlamydophila pneumoniae SET domain gene was clarified to be coincidently expressed with hctA and hctB genes encoding chlamydial histone H1-like proteins, Hc1 and Hc2, respectively. The SET domain protein (cpnSET) is localized in chlamydial cells and interacts with Hc1 and Hc2 through the C-terminal SET domain. As expected from conservation of catalytic sites in cpnSET, it functions as a protein methyltransferase to murine histone H3 and Hc1. However, little is known about protein methylation in the molecular pathogenesis of chlamydial infection, cpnSET may play an important role in chlamydial cell maturation due to modification of chlamydial histone H1-like proteins.

The aminocoumarin antibiotic clorobiocin contains an unusual branched deoxysugar with a 5,5-gem-dimethyl structure. Inactivation of the putative C-methyltransferase gene cloU was carried out, which led to the loss of the axial methyl group at C-5 of this deoxysugar moiety. This result establishes the function of cloU, and at the same time it proves that the biosynthesis of the deoxysugar moiety of clorobiocin proceeds via a 3,5-epimerization of the dTDP-4-keto-6-deoxyglucose intermediate. The inactivation was carried out on a cosmid which contained the entire clorobiocin biosynthetic gene cluster. Expression of the modified cluster in a heterologous host led to the formation of desmethyl-clorobiocin and a structural isomer thereof. Both compounds were isolated on a preparative scale, their structures were elucidated by [sup.1]H-NMR and mass spectroscopy and their antibacterial activity was assayed.

A putative virulence-associated DNA methyltransferase (MTase) gene conducted on a novel 22.79-kb pathogenicity island-like element (VPAI) in Vibrio parahaemolyticus is identified. The V. parahaemolyticus MTase gene was shown by PCR to be prevalent (.98%) in pandemic thermostable direct hemolysin gene-positive isolates, which suggests that VPAI might confer unique virulence traits to pandemic strains of V. parahaemolyticus.

The mechanism of DNA cytosine-5-methylation catalyzed by the bacterial M.Hhal enzyme has been considered as a stepwise nucleophilic addition of Cys-81-[S.sup.-] to cytosine C6 followed by C5 nucleophilic replacement of the methyl of S-adenosyl-L-methionine to produce 5-methyl-6-Cys-81-S-5,6-dihydrocytosine. In this study, we show that the reaction is concerted from a series of energy calculations by using the quantum mechanical/molecular mechanical hybrid method. Deprotonation of 5-methyl-6-Cys-81-S-5,6-dihydrocytosine and expulsion of Cys-81-S provides the product DNA 5-methylcytosine. A required base catalyst for this deprotonation is not available as a member of the active site structure. A water channel between the active site and bulk water allows entrance of solvent to the active site. Hydroxide at [10.sup.-7] mole fraction (pH = 7) is shown to be sufficient for the required catalysis. We also show that Glu-119-C[O.sub.2]H can divert the reaction by protonating cytosine N3 when Cys-81-S- attacks cytosine, to form the 6-Cys-81-S-3-hydrocytosine. The reactants and 6-Cys-81-S-3-hydrocytosine product are in rapid equilibrium, and this explains the observed hydrogen exchange of cytosine with solvent. computational

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2005.12.054 Byline: Jonathan R. Chubb (a)(h)(i), Gareth Bloomfield (b)(c), Qikai Xu (d)(e), Markus Kaller (f), Al Ivens (b)(c), Jason Skelton (b)(c), Bryan M. Turner (g), Wolfgang Nellen (f), Gad Shaulsky (d)(e), Robert R. Kay (b)(c), Wendy A. Bickmore (h), Robert H. Singer (a) Keywords: Chromatin; Dictyostelium; Set1; Lysine 4 methylation; Gene cluster; Clock Abstract: Histone-modifying enzymes have enormous potential as regulators of the large-scale changes in gene expression occurring during differentiation. It is unclear how different combinations of histone modification coordinate regimes of transcription during development. We show that different methylation states of lysine 4 of histone H3 (H3K4) mark distinct developmental phases of the simple eukaryote, Dictyostelium. We demonstrate that the enzyme responsible for all mono, di and tri-methylation of H3K4 is the Dictyostelium homolog of the Set1 histone methyltransferase. In the absence of Set1, cells display unusually rapid development, characterized by precocious aggregation of amoebae into multicellular aggregates. Early differentiation markers are abundantly expressed in growing set1 cells, indicating the differentiation program is ectopically activated during growth. This phenotype is caused specifically by the loss of Set1 catalytic activity. Set1 mutants induce premature differentiation in wild-type cells, indicating Set1 regulates production of an extra-cellular factor required for the correct perception of growth conditions. Microarray analysis of the set1 mutants reveals genomic clustering of mis-expressed genes, suggesting a requirement for Set1 in the regulation of chromatin-mediated events at gene clusters. Author Affiliation: (a) Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, The Bronx, NY 10461, USA (b) MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK (c) The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK (d) Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030, USA (e) Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA (f) Abt. Genetik, Universitat Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel, Germany (g) Chromatin and Gene Expression Group, Anatomy Department, University of Birmingham Medical School, Birmingham B15 2TT, UK (h) MRC Human Genetics Unit, Western General Hospital, Crewe Road, Edinburgh EH4 2XU, UK (i) Division of Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK Article History: Received 3 November 2005; Accepted 30 December 2005

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.cell.2005.10.023 Byline: Michael J. Carrozza (1), Bing Li (1), Laurence Florens (1), Tamaki Suganuma (1), Selene K. Swanson (1), Kenneth K. Lee (1), Wei-Jong Shia (1), Scott Anderson (2), John Yates (2), Michael P. Washburn (1), Jerry L. Workman (1) Abstract: Yeast Rpd3 histone deacetylase plays an important role at actively transcribed genes. We characterized two distinct Rpd3 complexes, Rpd3L and Rpd3S, by MudPIT analysis. Both complexes shared a three subunit core and Rpd3L contains unique subunits consistent with being a promoter targeted corepressor. Rco1 and Eaf3 were subunits specific to Rpd3S. Mutants of RCO1 and EAF3 exhibited increased acetylation in the FLO8 and STE11 open reading frames (ORFs) and the appearance of aberrant transcripts initiating within the body of these ORFs. Mutants in the RNA polymerase II-associated SET2 histone methyltransferase also displayed these defects. Set2 functioned upstream of Rpd3S and the Eaf3 methyl-histone binding chromodomain was important for recruitment of Rpd3S and for deacetylation within the STE11 ORF. These data indicate that Pol II-associated Set2 methylates H3 providing a transcriptional memory which signals for deacetylation of ORFs by Rpd3S. This erases transcription elongation-associated acetylation to suppress intragenic transcription initiation. Author Affiliation: (1) Stowers Institute for Medical Research, 1000 East 50.sup.th Street, Kansas City, Missouri 64110 (2) The Scripps Research Institute, 10550 North Torrey Pines Road, LaJolla, California 92037 Article History: Received 31 May 2005; Revised 19 September 2005; Accepted 20 October 2005 Article Note: (miscellaneous) Published: November 17, 2005

Molecular dynamics (MD) simulations of Hhal DNA methyltransferase and statistical coupling analysis (SCA) data on the DNA cytosine methyltransferase family were combined to identify residues that are coupled by coevolution and motion. The highest ranking correlated pairs from the data matrix product (SCA-MD) are colocalized and form stabilizing interactions; the anticorrelated pairs are separated on average by 30 [Angstrom] and form a clear focal point centered near the active site. We suggest that these distal anti-correlated pairs are involved in mediating active-site compressions that may be important for catalysis. Mutants that disrupt the implicated interactions support the validity of our combined SCA*MD approach. anticorrelated motion | correlated motion | M.Hhal | statistical coupling analysis

The ribosomal protein L11 in bacteria is posttranslationally trimethylated at multiple amino acid positions by the L11 methyltransferase PrmA, the product of the prmA gene. The role of L11 methylation in ribosome function or assembly has yet to be determined, although the deletion of Escherichia coli prmA has no apparent phenotype. We have constructed a mutant of the extreme thermophile Thermus thermophilus in which the prmA gene has been disrupted with the htk gene encoding a heat-stable kanamycin adenyltransferase. This mutant shows no growth defects, indicating that T. thermophilus PrmA, like its E. coli homolog, is dispensable. Ribosomes prepared from this mutant contain unmethylated L11, as determined by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and are effective substrates for in vitro methylation by cloned and purified T. thermophilus PrmA. MALDI-TOF MS also revealed that T. thermophilus L11 contains a total of 12 methyl groups, in contrast to the 9 methyl groups found in E. coli L11. Finally, we found that, as with the E. coli methyltransferase, the ribosomal protein L11 dissociated from ribosomes is a more efficient substrate for in vitro methylation by PrmA than intact 70S ribosomes, suggesting that methylation in vivo occurs on free L11 prior to its incorporation into ribosomes.

Research has been conducted on the SsuDAT1I restriction-modification system containing methyltransferases and endonucleases. The field isolate of Streptococcus suis serotype 2 has been investigated and the results indicate the presence of isoschizomers of this system in this locus and that different serotypes have been examined.

Research has been conducted on the oleandomycin, a macrolide antibiotic produced by Streptomyces antibioticus. The expression of oleY and the purification of OleY methyltransferase have been carried out and the results indicate that that methylation occurs at the C-3-O position of the neutral sugar generating L-oleandrose during the oleandomycin biosynthesis by S. antibioticus.

Research has been conducted on the PvuII restriction-modification system. Results demonstrate that the premature expression of pvuIIC prevents PvuII gene establishment.

The N5-methyltetrahydromethanopterin:coenzyme M methyltransferase, a membrane-bound cobalamin-containing protein of Methanosarcina mazei Gol, after partial purification requires a minimum of one iron-sulfur cluster for transmethylation in addition to the cobamide. Methyltransferase activity at different controlled redox potentials shows their activation by a one-electron reduction with half maximum activity at standard reduction potential values of -235 millivolts and -450 millivolts for reactions with and without ATP respectively.

The domain V RNA Bacillus subtilis is transcribed in vitro by cloning and using the DNA sequence, which encodes 23S rRNA domain nucleotides 2036 to 2672, as a template. The RNA transcripts enable methylation of adenine 2085 by the Erm SF methyltransferase. The Erm SF methyltransferase resists the action of macrolide-lincosamide-streptogranin B group of antibiotics on Streptomyces fradiae. This indicates that RNA sequences are not required for specific methylation of adenine, which resists the action of antibiotics.

The domain V of 23S rRNA consists of all the primary features essential for the recognition of ErmE methyltransferase in Saccharopolyspora erythraea. The N-6 position of adenine 2058 in domain V of 23S rRNA is dimethylated by the ErmE methyltransferase. The ErmE methyltransferase is generated by the erythromycin-producing actinomycetes in Saccharopolyspora. This indicates that ErmE methyltransferase confers the resistance to erythromycin.

The presence of the RecBCD protein, which ensures the viability of the Escherichia coli dam mutant, facilitates DNA repair. Recombination genes such as recQ+, recO+, recN+ and recF+ are important for the survival of the recBC sbcBC dam mutant. SOS gene subinduction in dam mutants is not inhibited by the mutations mutS, mutL and mutH.

Overexpression of a gene encoding an exogenous mouse DNA methyltransferase leads to transformed NIH 3T3 mouse fibroblasts. The transformation is characterized by enhanced DNA methylation and tumorigenic changes. Enhanced DNA methyltransferase activity, a characteristic feature of tumor progression, provides the molecular basis for carcinogenesis. This postulate can be used as a frame of reference for further research in this field.

An experiment was conducted to demonstrate that M.Eco RII joins with azaC DNA in vivo and that there is no connection between the enzyme quantity and the influence of the drug on the cells, to prove the theory that strand interchange catalyzed by the Rec A protein in vitro is restricted by the M.Eco RII bound to DNA. This enzyme attaches to the azaC DNA in vivo, and this attachment takes place at the most decreased concentration of the drug. No connection between the enzyme quantity existing in the cell initially and sensitivity of the cell to aza cyd was seen, but sensitivity to aza Cyd was connected to the total ecoRII M structural gene.

A genetic reversion assay to study the increase in C-to-T mutations at CG sites in Escherichia coli by HpaII methyltransferase (MTase) is described. HpaII and SssI MTases can also convert cytosine to uracil in vitro. Thus to define the methylation at C-5 of the cytosine in DNA as being intrinsically mutagenic the occurrence of mutagenic hot spots at all methylated cytosines in DNA must be taken to be true.

The studies about the maintenance of methylation process during early mammalian embryogenesis vital for embryonic development are reported. Results showed that DNA methyltransferase (Dnmt1) and not Dnmt2a or Dnmt3b contributes to the regulation of methylation at genomic imprints during preimplantation development.

The study explains the synthesis and characterization of SafC, a catechol 4-O-methyltransferase protein, which is commonly used for the biosynthesis of various saframycin products. SafC has the ability to methylate a variety of catechols and hence can be used in many medical and biological applications.

A study demonstrated that pabIM, which is similar to M and S genes of type I system, encodes a functional DNA methyltransferase (M.PabI) generating 5'-GTm6AC. The results showed that this unique methyltransferase and PabI constitute a type II restriction-modification gene complex that entered the Pyrococcus abyssi genome relatively recently.