Effect of C5-Methylation of Cytosine on the UV-Induced Reactivity of Duplex DNA: Conformational and Electronic Factors(163 visite) Banyasz A, Esposito L, Douki T, Perron M, Lepori C, Improta R, Markovitsi D
J Phys Chem B (ISSN: 1520-6106, 1520-5207), 2016 May 12; 120(18): 4232-4242.
Tipo di articolo: Journal Article,
Impact factor: 3.177, Impact factor a 5 anni: 3.177
C5-methylation of cytosines is strongly correlated with UV-induced mutations detected in skin cancers. Mutational hot-spots appearing at TCG sites are due to the formation of pyrimidine cyclobutane dimers (CPDs). The present study, performed for the model DNA duplex (TCGTA)3.(TACGA)3 and the constitutive single strands, examines the factors underlying the effect of C5-methylation on pyrimidine dimerization at TCG sites. This effect is quantified for the first time by quantum yields varphi. They were determined following irradiation at 255, 267, and 282 nm and subsequent photoproduct analysis using HPLC coupled to mass spectrometry. C5-methylation leads to an increase of the CPD quantum yield up to 80% with concomitant decrease of that of pyrimidine(6-4) pyrimidone adducts (64PPs) by at least a factor of 3. The obtained varphi values cannot be explained only by the change of the cytosine absorption spectrum upon C5-methylation. The conformational and electronic factors that may affect the dimerization reaction are discussed in light of results obtained by fluorescence spectroscopy, molecular dynamics simulations, and quantum mechanical calculations. Thus, it appears that the presence of an extra methyl on cytosine affects the sugar puckering, thereby enhancing conformations of the TC step that are prone to CPD formation but less favorable to 64PPs. In addition, C5-methylation diminishes the amplitude of conformational motions in duplexes; in the resulting stiffer structure, pipi* excitations may be transferred from initially populated exciton states to reactive pyrimidines giving rise to CPDs.
Petraglia F, Singh AA, Carafa V, Nebbioso A, Conte M, Scisciola L, Valente S, Baldi A, Mandoli A, Petrizzi VB, Ingenito C, De Falco S, Cicatiello V, Apicella I, Janssen-megens EM, Kim B, Yi G, Logie C, Heath S, Ruvo M, Wierenga ATJ, Flicek P, Yaspo ML, Della Valle V, Bernard O, Tomassi S, Novellino E, Feoli A, Sbardella G, Gut I, Vellenga E, Stunnenberg HG, Mai A, Martens JHA, Altucci L * Combined HAT/EZH2 modulation leads to cancer-selective cell death(145 visite) Oncotarget (ISSN: 1949-2553electronic, 1949-2553linking), 2018 May 22; 9(39): 25630-25646. Impact Factor:5.008 DettagliEsporta in BibTeXEsporta in EndNote
222 Records (203 escludendo Abstract e Conferenze). Impact factor totale: 787.899 (751.424 escludendo Abstract e Conferenze). Impact factor a 5 anni totale: 850.341 (812.275 escludendo Abstract e Conferenze).