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[PMID]: 29242886 [Au] Autor: Romero EE; Hernandez FE [Ad] Endereço: Department of Chemistry, University of Central Florida, P. O. Box 162366, Orlando, Florida 32816-2366, USA. florencio.hernandez@ucf.edu. [Ti] Título: Solvent effect on the intermolecular proton transfer of the Watson and Crick guanine-cytosine and adenine-thymine base pairs: a polarizable continuum model study. [So] Source: Phys Chem Chem Phys;20(2):1198-1209, 2018 Jan 03. [Is] ISSN: 1463-9084 [Cp] País de publicação: England [La] Idioma: eng [Ab] Resumo: Herein we present our results on the study of the double proton transfer (DPT) mechanism in the adenine-thymine (AT) and guanine-cytosine (GC) base pairs, both in gas phase and in solution. The latter was modeled using the polarizable continuum method (PCM) in different solvents. According to our DFT calculations, the DPT may occur for both complexes in a stepwise mechanism in condensate phase. In gas phase only the GC base pair exhibits a concerted DPT mechanism. Using the Wigner's tunneling corrections to the transition state theory we demonstrate that such corrections are important for the prediction of the rate constants of both systems in gas and in condensate phase. We also show that (i) as the polarity of the medium decreases the equilibrium constant of the DPT reaction increases in both complexes, and (ii) that the equilibrium constant in the GC complex is four orders of magnitude larger than in AT. This observation suggests that the spontaneous mutations in DNA base pairs are more probable in GC than in AT. [Mh] Termos MeSH primário: Pareamento de Bases DNA/química Modelos Moleculares [Mh] Termos MeSH secundário: Adenina Citosina Guanina Prótons Solventes Timina [Pt] Tipo de publicação: JOURNAL ARTICLE [Nm] Nome de substância: 0 (Protons); 0 (Solvents); 5Z93L87A1R (Guanine); 8J337D1HZY (Cytosine); 9007-49-2 (DNA); JAC85A2161 (Adenine); QR26YLT7LT (Thymine) [Em] Mês de entrada: 1802 [Cu] Atualização por classe: 180209 [Lr] Data última revisão: 180209 [Sb] Subgrupo de revista: IM [Da] Data de entrada para processamento: 171216 [St] Status: MEDLINE [do] DOI: 10.1039/c7cp05356h

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[PMID]: 29190698 [Au] Autor: Foksinski M; Zarakowska E; Gackowski D; Skonieczna M; Gajda K; Hudy D; Szpila A; Bialkowski K; Starczak M; Labejszo A; Czyz J; Rzeszowska-Wolny J; Olinski R [Ad] Endereço: Department of Clinical Biochemistry, Faculty of Pharmacy, L. Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Torun, Bydgoszcz, Poland. [Ti] Título: Profiles of a broad spectrum of epigenetic DNA modifications in normal and malignant human cell lines: Proliferation rate is not the major factor responsible for the 5-hydroxymethyl-2'-deoxycytidine level in cultured cancerous cell lines. [So] Source: PLoS One;12(11):e0188856, 2017. [Is] ISSN: 1932-6203 [Cp] País de publicação: United States [La] Idioma: eng [Ab] Resumo: Active demethylation of 5-methylcytosine moiety in DNA occurs by its sequential oxidation to 5-hydroxymethylcytosine, 5-formylcytosine and 5-carboxycytosine, catalysed by enzymes of the Ten-Eleven Translocation family proteins (TETs 1, 2 and 3). Here we analyzed for the first time all the intermediate products of DNA demethylation pathway in the form of deoxynucleosides (5-methyl-2'-deoxycytidine, 5-(hydroxymethyl)-2'-deoxycytidine, 5-formyl-2'-deoxycytidine and 5-carboxy-2'-deoxycytidine as well as 5-(hydroxymethyl)-2'-deoxyuridine) using automated isotope-dilution online two-dimensional ultra-performance liquid chromatography with tandem mass spectrometry. DNA was isolated from human malignant cell lines of colon adenocarcinoma (HCT 116), melanoma (Me45), myelogenous leukemia bone marrow blasts (K562), EBV-positive Burkitt's lymphoma lymphoblasts (Raji), EBV-negative Burkitt's lymphoma lymphoblasts (male-CA46 and female-ST486), as well as normal neonatal dermal fibroblasts (NHDF-Neo). The expression levels of TET1, TET2, TET3, SMUG1, and TDG genes were also assayed by RT-qPCR. Our results show a global erasure of 5-hydroxymethyl-2'-deoxycytidine and 5-carboxy-2'-deoxycytidine in DNA of cultured cells compared with DNA from primary malignant tissue. Moreover, malignant cells in culture have a quite different DNA epigenetic profile than cultured normal cells, and different types of malignant cells display different and characteristic profiles of DNA epigenetic marks. Similar analyses of a broader spectrum of epigenetic modifications, not restricted to 5-methyl-2'-deoxycytidine, could lead to better understanding of the mechanism(s) responsible for emergence of different types of cancer cells. [Mh] Termos MeSH primário: Proliferação Celular/efeitos dos fármacos DNA/genética Desoxicitidina/análogos & derivados Epigênese Genética [Mh] Termos MeSH secundário: Linhagem Celular Tumoral Cromatografia Líquida Citosina/análise DNA/química Desoxicitidina/farmacologia Seres Humanos Reação em Cadeia da Polimerase em Tempo Real Reação em Cadeia da Polimerase Via Transcriptase Reversa Espectrometria de Massas em Tandem Timina/análise [Pt] Tipo de publicação: JOURNAL ARTICLE [Nm] Nome de substância: 0 (5-hydroxymethyl-2'-deoxycytidine); 0W860991D6 (Deoxycytidine); 8J337D1HZY (Cytosine); 9007-49-2 (DNA); QR26YLT7LT (Thymine) [Em] Mês de entrada: 1712 [Cu] Atualização por classe: 171226 [Lr] Data última revisão: 171226 [Sb] Subgrupo de revista: IM [Da] Data de entrada para processamento: 171201 [St] Status: MEDLINE [do] DOI: 10.1371/journal.pone.0188856

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[PMID]: 28817834 [Au] Autor: Chen Y; Wang DD; Wu YP; Su D; Zhou TY; Gai RH; Fu YY; Zheng L; He QJ; Zhu H; Yang B [Ad] Endereço: Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, Institute of Pharmacology &Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China. [Ti] Título: MDM2 promotes epithelial-mesenchymal transition and metastasis of ovarian cancer SKOV3 cells. [So] Source: Br J Cancer;117(8):1192-1201, 2017 Oct 10. [Is] ISSN: 1532-1827 [Cp] País de publicação: England [La] Idioma: eng [Ab] Resumo: BACKGROUND: Metastasis accounts for the most lethal reason for the death of ovarian cancer patients, but remains largely untreated. Epithelial-mesenchymal transition (EMT) is critical for the conversion of early-stage ovarian tumours into metastatic malignancies. Thus the exploration of the signalling pathways promoting EMT would open potential opportunities for the treatment of metastatic ovarian cancer. Herein, the putative role of MDM2 in regulating EMT and metastasis of ovarian cancer SKOV3 cells was investigated. METHODS: The regulatory effects by MDM2 on cell motility was emulated by wound-healing and transwell assays. The effects on EMT transition and Smad pathway were studied by depicting the expression levels of epithelial marker E-cadherin as well as key components of Smad pathway. To evaluate the clinical relevance of our findings, the correlation of MDM2 expression levels with the stages of 104 ovarian cancer patients was investigated by immunohistochemistry assay. RESULTS: We demonstrate that MDM2 functions as a key factor to drive EMT and motility of ovarian SKOV3 cells, by facilitating the activation of TGF-ß-Smad pathway, which results in the increased transcription of snail/slug and the subsequent loss of E-cadherin levels. Such induction of EMT is sustained in either E3 ligase-depleted MDM2 or E3 ligase inhibitor HLI-373-treated cells, while being impaired by the N-terminal deletion of MDM2, which is also reflected by the inhibitory effects against EMT by Nutlin-3a, the N-terminal targeting agent. The expression levels of MDM2 is highly correlated with the stages of the ovarian cancer patients, and the higher expression of MDM2 together with TGFB are closely correlated with poor prognosis and predict a high risk of ovarian cancer patients. CONCLUSIONS: This study suggests that MDM2 activates Smad pathway to promote EMT in ovarian cancer metastasis, and targeting the N-terminal of MDM2 can reprogram EMT and impede the mobility of cancer cells. [Mh] Termos MeSH primário: Carcinoma/genética Transição Epitelial-Mesenquimal/genética Neoplasias Ovarianas/genética Proteínas Proto-Oncogênicas c-mdm2/genética [Mh] Termos MeSH secundário: Aminoquinolinas/farmacologia Western Blotting Caderinas/metabolismo Carcinoma/metabolismo Carcinoma/patologia Linhagem Celular Tumoral Movimento Celular/genética Transição Epitelial-Mesenquimal/efeitos dos fármacos Feminino Imunofluorescência Técnicas de Silenciamento de Genes Seres Humanos Imuno-Histoquímica Metástase Neoplásica Estadiamento de Neoplasias Neoplasias Ovarianas/metabolismo Neoplasias Ovarianas/patologia Proteínas Proto-Oncogênicas c-mdm2/efeitos dos fármacos Proteínas Proto-Oncogênicas c-mdm2/metabolismo Reação em Cadeia da Polimerase em Tempo Real Transdução de Sinais Proteínas Smad/metabolismo Fatores de Transcrição da Família Snail/genética Timina/análogos & derivados Timina/farmacologia Fator de Crescimento Transformador beta/metabolismo [Pt] Tipo de publicação: JOURNAL ARTICLE [Nm] Nome de substância: 0 (5-(3-dimethylaminopropylamino)-3,10-dimethyl-10H-pyrimido(4,5-b)quinoline-2,4-dione); 0 (Aminoquinolines); 0 (CDH1 protein, human); 0 (Cadherins); 0 (SNAI1 protein, human); 0 (Smad Proteins); 0 (Snail Family Transcription Factors); 0 (Transforming Growth Factor beta); EC 2.3.2.27 (MDM2 protein, human); EC 2.3.2.27 (Proto-Oncogene Proteins c-mdm2); QR26YLT7LT (Thymine) [Em] Mês de entrada: 1710 [Cu] Atualização por classe: 171109 [Lr] Data última revisão: 171109 [Sb] Subgrupo de revista: IM [Da] Data de entrada para processamento: 170818 [St] Status: MEDLINE [do] DOI: 10.1038/bjc.2017.265

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[PMID]: 28720682 [Au] Autor: Do H; Molania R; Mitchell PL; Vaiskunaite R; Murdoch JD; Dobrovic A [Ad] Endereço: Translational Genomics and Epigenomics Laboratory, Olivia Newton-John Cancer Research Institute, Melbourne, Australia; Hongdo.Do@onjcri.org.au Alex.Dobrovic@onjcri.org.au. [Ti] Título: Reducing Artifactual T790M Mutations in DNA from Formalin-Fixed Paraffin-Embedded Tissue by Use of Thymine-DNA Glycosylase. [So] Source: Clin Chem;63(9):1506-1514, 2017 Sep. [Is] ISSN: 1530-8561 [Cp] País de publicação: United States [La] Idioma: eng [Ab] Resumo: BACKGROUND: False-positive T790M mutations have been reported in formalin-fixed lung tumors, but the cause of the false positives has not been identified. The T790M mutation results from a C>T change at the cytosine of a CpG dinucleotide. The presence or absence of methylation at this cytosine has different consequences following deamination, resulting in a thymine or uracil, respectively, both of which however result in an artifactual change. Uracil-DNA glycosylase (UDG) can be used to eliminate DNA templates with uracil residues but is not active against artifactual thymines. We therefore investigated the use of thymine-DNA glycosylase (TDG) to reduce artifactual T790M mutations. METHODS: Formalin-fixed normal lung tissues and lung squamous cell carcinomas were tested to measure the frequency of false-positive mutations by use of droplet digital PCR before and after treatment with either UDG or TDG. Methylation at the cytosine at T790 was assessed by pyrosequencing and by analysis of public databases. RESULTS: Artifactual T790M mutations were detected in all of the archival formalin-fixed normal lung and lung squamous cell carcinomas at mutant allele frequencies of 1% or lower. The cytosine at T790 showed high levels of methylation in all lung cancer samples and normal tissues. Pretreatment of the formalin-fixed DNA with either UDG or TDG reduced the false T790M mutations, but a greater reduction was seen with the TDG treatment. CONCLUSIONS: Both U:G and T:G lesions in formalin-fixed tissue are sources of false-positive T790M mutations. This is the first report of the use of TDG to reduce sequence artifacts in formalin-fixed DNA and is applicable to the accurate detection of mutations arising at methylated cytosines. [Mh] Termos MeSH primário: DNA Glicosilases/metabolismo Erros de Diagnóstico/prevenção & controle Genes erbB-1/genética Técnicas de Diagnóstico Molecular/métodos Mutação/genética Inclusão em Parafina [Mh] Termos MeSH secundário: Linhagem Celular Tumoral Reações Falso-Positivas Seres Humanos Técnicas de Diagnóstico Molecular/normas Neoplasias/diagnóstico Neoplasias/genética Timina/química [Pt] Tipo de publicação: JOURNAL ARTICLE [Nm] Nome de substância: EC 3.2.2.- (DNA Glycosylases); QR26YLT7LT (Thymine) [Em] Mês de entrada: 1709 [Cu] Atualização por classe: 170907 [Lr] Data última revisão: 170907 [Sb] Subgrupo de revista: IM [Da] Data de entrada para processamento: 170720 [St] Status: MEDLINE [do] DOI: 10.1373/clinchem.2017.271932

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[PMID]: 28575445 [Au] Autor: Melikishvili M; Fried MG [Ad] Endereço: Center for Structural Biology, Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40536, USA. [Ti] Título: Quaternary interactions and supercoiling modulate the cooperative DNA binding of AGT. [So] Source: Nucleic Acids Res;45(12):7226-7236, 2017 Jul 07. [Is] ISSN: 1362-4962 [Cp] País de publicação: England [La] Idioma: eng [Ab] Resumo: Human O6-alkylguanine-DNA alkyltransferase (AGT) repairs mutagenic O6-alkylguanine and O4-alkylthymine adducts in single-stranded and duplex DNAs. The search for these lesions, through a vast excess of competing, unmodified genomic DNA, is a mechanistic challenge that may limit the repair rate in vivo. Here, we examine influences of DNA secondary structure and twist on protein-protein interactions in cooperative AGT complexes formed on lesion-free DNAs that model the unmodified parts of the genome. We used a new approach to resolve nearest neighbor (nn) and long-range (lr) components from the ensemble-average cooperativity, ωave. We found that while nearest-neighbor contacts were significant, long-range interactions dominated cooperativity and this pattern held true whether the DNA was single-stranded or duplex. Experiments with single plasmid topoisomers showed that the average cooperativity was sensitive to DNA twist, and was strongest when the DNA was slightly underwound. This suggests that AGT proteins are optimally juxtaposed when the DNA is near its torsionally-relaxed state. Most striking was the decline of binding stoichiometry with linking number. As stoichiometry and affinity differences were not correlated, we interpret this as evidence that supercoiling occludes AGT binding sites. These features suggest that AGT's lesion-search distributes preferentially to sites containing torsionally-relaxed DNA, in vivo. [Mh] Termos MeSH primário: Reparo do DNA DNA/química Guanina/análogos & derivados O(6)-Metilguanina-DNA Metiltransferase/química Timina/análogos & derivados [Mh] Termos MeSH secundário: Sítios de Ligação Clonagem Molecular DNA/metabolismo DNA Topoisomerases Tipo I/química DNA Topoisomerases Tipo I/metabolismo Escherichia coli/genética Escherichia coli/metabolismo Expressão Gênica Guanina/metabolismo Seres Humanos Cinética Modelos Moleculares Mutação O(6)-Metilguanina-DNA Metiltransferase/genética O(6)-Metilguanina-DNA Metiltransferase/metabolismo Ligação Proteica Conformação Proteica em alfa-Hélice Domínios e Motivos de Interação entre Proteínas Estrutura Quaternária de Proteína Proteínas Recombinantes/química Proteínas Recombinantes/genética Proteínas Recombinantes/metabolismo Especificidade por Substrato Termodinâmica Timina/metabolismo [Pt] Tipo de publicação: JOURNAL ARTICLE [Nm] Nome de substância: 0 (Recombinant Proteins); 5Z93L87A1R (Guanine); 9007-49-2 (DNA); EC 2.1.1.63 (O(6)-Methylguanine-DNA Methyltransferase); EC 5.99.1.2 (DNA Topoisomerases, Type I); QR26YLT7LT (Thymine) [Em] Mês de entrada: 1710 [Cu] Atualização por classe: 171017 [Lr] Data última revisão: 171017 [Sb] Subgrupo de revista: IM [Da] Data de entrada para processamento: 170603 [St] Status: MEDLINE [do] DOI: 10.1093/nar/gkx223

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[PMID]: 28525579 [Au] Autor: Wang K; Taylor JA [Ad] Endereço: Department of Chemistry, Washington University, St Louis, MO 63130, USA. [Ti] Título: Modulation of cyclobutane thymine photodimer formation in T11-tracts in rotationally phased nucleosome core particles and DNA minicircles. [So] Source: Nucleic Acids Res;45(12):7031-7041, 2017 Jul 07. [Is] ISSN: 1362-4962 [Cp] País de publicação: England [La] Idioma: eng [Ab] Resumo: Cyclobutane pyrimidine dimers (CPDs) are DNA photoproducts linked to skin cancer, whose mutagenicity depends in part on their frequency of formation and deamination. Nucleosomes modulate CPD formation, favoring outside facing sites and disfavoring inward facing sites. A similar pattern of CPD formation in protein-free DNA loops suggests that DNA bending causes the modulation in nucleosomes. To systematically study the cause and effect of nucleosome structure on CPD formation and deamination, we have developed a circular permutation synthesis strategy for positioning a target sequence at different superhelix locations (SHLs) across a nucleosome in which the DNA has been rotationally phased with respect to the histone octamer by TG motifs. We have used this system to show that the nucleosome dramatically modulates CPD formation in a T11-tract that covers one full turn of the nucleosome helix at seven different SHLs, and that the position of maximum CPD formation at all locations is shifted to the 5΄-side of that found in mixed-sequence nucleosomes. We also show that an 80-mer minicircle DNA using the same TG-motifs faithfully reproduces the CPD pattern in the nucleosome, indicating that it is a good model for protein-free rotationally phased bent DNA of the same curvature as in a nucleosome, and that bending is modulating CPD formation. [Mh] Termos MeSH primário: DNA Circular/química Histonas/química Nucleossomos/efeitos da radiação Dímeros de Pirimidina/agonistas Timina/química [Mh] Termos MeSH secundário: Animais Galinhas DNA Circular/isolamento & purificação Desaminação Eritrócitos/química Histonas/metabolismo Seres Humanos Mutagênese Conformação de Ácido Nucleico Nucleossomos/química Nucleossomos/metabolismo Dímeros de Pirimidina/química Dímeros de Pirimidina/metabolismo Timina/metabolismo Raios Ultravioleta [Pt] Tipo de publicação: JOURNAL ARTICLE [Nm] Nome de substância: 0 (DNA, Circular); 0 (Histones); 0 (Nucleosomes); 0 (Pyrimidine Dimers); QR26YLT7LT (Thymine) [Em] Mês de entrada: 1710 [Cu] Atualização por classe: 171011 [Lr] Data última revisão: 171011 [Sb] Subgrupo de revista: IM [Da] Data de entrada para processamento: 170520 [St] Status: MEDLINE [do] DOI: 10.1093/nar/gkx427

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[PMID]: 28362220 [Au] Autor: Elgemeie GH; Farag AB [Ad] Endereço: a Chemistry Department, Faculty of Science , Helwan University , Helwan , Cairo , Egypt. [Ti] Título: Design, synthesis, and in vitro anti-hepatocellular carcinoma of novel thymine thioglycoside analogs as new antimetabolic agents. [So] Source: Nucleosides Nucleotides Nucleic Acids;36(5):328-342, 2017 May 04. [Is] ISSN: 1532-2335 [Cp] País de publicação: United States [La] Idioma: eng [Ab] Resumo: A first reported direct method for preparation of thymine thioglycoside analogs utilizing novel pyrimidine-2(1H)-thiones and α-bromoglucose or α-bromogalactose tetraacetate as starting components is described. The synthetic potential of the method is demonstrated. The evaluation of antiproliferative activity against HepG-2 cell lines (Liver carcinoma cell lines) shows that most of the compounds have high antitumor activities especially 6b, 6e, 11b, and 12b. Moreover, molecular modelings of these compounds reveal that they have high binding affinity through hydrogen bond interaction with the binding pocket of thymidylate synthase dihydrofolate reductase (TS-DHFR). [Mh] Termos MeSH primário: Antineoplásicos/química Antineoplásicos/farmacologia Carcinoma Hepatocelular/tratamento farmacológico Desenho de Drogas Neoplasias Hepáticas/tratamento farmacológico Tioglicosídeos/química Tioglicosídeos/farmacologia [Mh] Termos MeSH secundário: Antineoplásicos/síntese química Carcinoma Hepatocelular/metabolismo Proliferação Celular/efeitos dos fármacos Ensaios de Seleção de Medicamentos Antitumorais Células Hep G2 Seres Humanos Fígado/efeitos dos fármacos Fígado/metabolismo Neoplasias Hepáticas/metabolismo Modelos Moleculares Complexos Multienzimáticos/metabolismo Tetra-Hidrofolato Desidrogenase/metabolismo Tioglicosídeos/síntese química Timidilato Sintase/metabolismo Timina/análogos & derivados Timina/síntese química Timina/farmacologia [Pt] Tipo de publicação: JOURNAL ARTICLE [Nm] Nome de substância: 0 (Antineoplastic Agents); 0 (Multienzyme Complexes); 0 (Thioglycosides); 0 (thymidylate synthase-dihydrofolate reductase); EC 1.5.1.3 (Tetrahydrofolate Dehydrogenase); EC 2.1.1.45 (Thymidylate Synthase); QR26YLT7LT (Thymine) [Em] Mês de entrada: 1709 [Cu] Atualização por classe: 170906 [Lr] Data última revisão: 170906 [Sb] Subgrupo de revista: IM [Da] Data de entrada para processamento: 170401 [St] Status: MEDLINE [do] DOI: 10.1080/15257770.2017.1287377

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[PMID]: 28320593 [Au] Autor: Yang L; Jian Y; Setlow P; Li L [Ad] Endereço: Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis (IUPUI), 402 North Blackford Street, Indianapolis, IN 46202, United States. [Ti] Título: Spore photoproduct within DNA is a surprisingly poor substrate for its designated repair enzyme-The spore photoproduct lyase. [So] Source: DNA Repair (Amst);53:31-42, 2017 May. [Is] ISSN: 1568-7856 [Cp] País de publicação: Netherlands [La] Idioma: eng [Ab] Resumo: DNA repair enzymes typically recognize their substrate lesions with high affinity to ensure efficient lesion repair. In UV irradiated endospores, a special thymine dimer, 5-thyminyl-5,6-dihydrothymine, termed the spore photoproduct (SP), is the dominant DNA photolesion, which is rapidly repaired during spore outgrowth mainly by spore photoproduct lyase (SPL) using an unprecedented protein-harbored radical transfer process. Surprisingly, our in vitro studies using SP-containing short oligonucleotides, pUC 18 plasmid DNA, and E. coli genomic DNA found that they are all poor substrates for SPL in general, exhibiting turnover numbers of 0.01-0.2min . The faster turnover numbers are reached under single turnover conditions, and SPL activity is low with oligonucleotide substrates at higher concentrations. Moreover, SP-containing oligonucleotides do not go past one turnover. In contrast, the dinucleotide SP TpT exhibits a turnover number of 0.3-0.4min , and the reaction may reach up to 10 turnovers. These observations distinguish SPL from other specialized DNA repair enzymes. To the best of our knowledge, SPL represents an unprecedented example of a major DNA repair enzyme that cannot effectively repair its substrate lesion within the normal DNA conformation adopted in growing cells. Factors such as other DNA binding proteins, helicases or an altered DNA conformation may cooperate with SPL to enable efficient SP repair in germinating spores. Therefore, both SP formation and SP repair are likely to be tightly controlled by the unique cellular environment in dormant and outgrowing spore-forming bacteria, and thus SP repair may be extremely slow in non-spore-forming organisms. [Mh] Termos MeSH primário: Bacillus subtilis/enzimologia Reparo do DNA DNA Bacteriano/metabolismo Desoxirribodipirimidina Fotoliase/metabolismo Timina/análogos & derivados [Mh] Termos MeSH secundário: Bacillus subtilis/genética Proteínas de Bactérias/metabolismo Dano ao DNA DNA Bacteriano/efeitos da radiação Escherichia coli/metabolismo Cinética Dímeros de Pirimidina/metabolismo Timina/metabolismo Raios Ultravioleta [Pt] Tipo de publicação: JOURNAL ARTICLE [Nm] Nome de substância: 0 (Bacterial Proteins); 0 (DNA, Bacterial); 0 (Pyrimidine Dimers); 28100-77-8 (5-thyminyl-5,6-dihydrothymine); EC 4.1.99.3 (Deoxyribodipyrimidine Photo-Lyase); QR26YLT7LT (Thymine) [Em] Mês de entrada: 1707 [Cu] Atualização por classe: 171026 [Lr] Data última revisão: 171026 [Sb] Subgrupo de revista: IM [Da] Data de entrada para processamento: 170322 [St] Status: MEDLINE

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[PMID]: 28158710 [Au] Autor: Hong S; Wang D; Horton JR; Zhang X; Speck SH; Blumenthal RM; Cheng X [Ad] Endereço: Department of Biochemistry, Emory University School of Medicine, 1510 Clifton Road, Atlanta, GA 30322, USA. [Ti] Título: Methyl-dependent and spatial-specific DNA recognition by the orthologous transcription factors human AP-1 and Epstein-Barr virus Zta. [So] Source: Nucleic Acids Res;45(5):2503-2515, 2017 Mar 17. [Is] ISSN: 1362-4962 [Cp] País de publicação: England [La] Idioma: eng [Ab] Resumo: T: Activator protein 1 (AP-1) is a transcription factor that recognizes two versions of a 7-base pair response element, either 5΄- GAG CA-3΄ or 5΄- GAG CA-3΄ (where M = 5-methylcytosine). These two elements share the feature that 5-methylcytosine and thymine both have a methyl group in the same position, 5-carbon of the pyrimidine, so each of them has two methyl groups at nucleotide positions 1 and 5 from the 5΄ end, resulting in four methyl groups symmetrically positioned in duplex DNA. Epstein-Barr Virus Zta is a key transcriptional regulator of the viral lytic cycle that is homologous to AP-1. Zta recognizes several methylated Zta-response elements, including meZRE1 (5΄- GAG C A-3΄) and meZRE2 (5΄- GAG G A-3΄), where a methylated cytosine occupies one of the inner thymine residues corresponding to the AP-1 element, resulting in the four spatially equivalent methyl groups. Here, we study how AP-1 and Zta recognize these methyl groups within their cognate response elements. These methyl groups are in van der Waals contact with a conserved di-alanine in AP-1 dimer (Ala265 and Ala266 in Jun), or with the corresponding Zta residues Ala185 and Ser186 (via its side chain carbon Cß atom). Furthermore, the two ZRE elements differ at base pair 6 (C:G versus G:C), forming a pseudo-symmetric sequence (meZRE1) or an asymmetric sequence (meZRE2). In vitro DNA binding assays suggest that Zta has high affinity for all four sequences examined, whereas AP-1 has considerably reduced affinity for the asymmetric sequence (meZRE2). We ascribe this difference to Zta Ser186 (a unique residue for Zta) whose side chain hydroxyl oxygen atom interacts with the two half sites differently, whereas the corresponding Ala266 of AP-1 Jun protein lacks such flexibility. Our analyses demonstrate a novel mechanism of 5mC/T recognition in a methylation-dependent, spatial and sequence-specific approach by basic leucine-zipper transcriptional factors. [Mh] Termos MeSH primário: Metilação de DNA Proteínas Proto-Oncogênicas c-jun/química Elementos de Resposta Transativadores/química [Mh] Termos MeSH secundário: 5-Metilcitosina/química Pareamento de Bases Sítios de Ligação DNA/química DNA/metabolismo Seres Humanos Ligação Proteica Multimerização Proteica Proteínas Proto-Oncogênicas c-jun/metabolismo Timina/química Transativadores/metabolismo Fator de Transcrição AP-1/química Fator de Transcrição AP-1/metabolismo [Pt] Tipo de publicação: JOURNAL ARTICLE [Nm] Nome de substância: 0 (BZLF1 protein, Herpesvirus 4, Human); 0 (Proto-Oncogene Proteins c-jun); 0 (Trans-Activators); 0 (Transcription Factor AP-1); 6R795CQT4H (5-Methylcytosine); 9007-49-2 (DNA); QR26YLT7LT (Thymine) [Em] Mês de entrada: 1708 [Cu] Atualização por classe: 170808 [Lr] Data última revisão: 170808 [Sb] Subgrupo de revista: IM [Da] Data de entrada para processamento: 170204 [St] Status: MEDLINE [do] DOI: 10.1093/nar/gkx057

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MEDLINE

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[PMID]: 28106332 [Au] Autor: Kotera N; Guillot R; Teulade-Fichou MP; Granzhan A [Ad] Endereço: CNRS UMR9187, INSERM U1196, Institut Curie, PSL Research University, 91405, Orsay, France. [Ti] Título: Copper(II)-Controlled Molecular Glue for Mismatched DNA. [So] Source: Chembiochem;18(7):618-622, 2017 Apr 04. [Is] ISSN: 1439-7633 [Cp] País de publicação: Germany [La] Idioma: eng [Ab] Resumo: Isothermal hybridization of two DNA strands bearing three thymine-thymine (T:T) mismatches can be brought about in the presence of a stoichiometric amount of a bis-naphthalene macrocycle, 2,7-BisNP-NH. This process can be reverted by addition of a Cu salt due to formation of a dinuclear metal complex which does not bind to DNA. Subsequent sequestration of Cu releases the macrocycle and restores the hybridization state of DNA strands, thus allowing implementation of a fast fluorescent two-state DNA switch. [Mh] Termos MeSH primário: Complexos de Coordenação/química Cobre/química DNA/química Substâncias Intercalantes/química Compostos Macrocíclicos/química Naftalenos/química Percloratos/química [Mh] Termos MeSH secundário: Pareamento Incorreto de Bases Ácido Edético/química Ligantes Desnaturação de Ácido Nucleico Hibridização de Ácido Nucleico Temperatura Ambiente Timina/química [Pt] Tipo de publicação: JOURNAL ARTICLE [Nm] Nome de substância: 0 (Coordination Complexes); 0 (Intercalating Agents); 0 (Ligands); 0 (Macrocyclic Compounds); 0 (Naphthalenes); 0 (Perchlorates); 13770-18-8 (copper(II) perchlorate); 789U1901C5 (Copper); 9007-49-2 (DNA); 9G34HU7RV0 (Edetic Acid); QR26YLT7LT (Thymine) [Em] Mês de entrada: 1709 [Cu] Atualização por classe: 170919 [Lr] Data última revisão: 170919 [Sb] Subgrupo de revista: IM [Da] Data de entrada para processamento: 170121 [St] Status: MEDLINE [do] DOI: 10.1002/cbic.201600675

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