Structure of (5′<i>S</i>)-8,5′-Cyclo-2′-deoxyguanosine in DNA

Huang, Hai; Das, Rajat S.; Basu, Ashis K.; Stone, Michael P.

doi:10.1021/ja207407n

Cited by 45 publications

(89 citation statements)

References 83 publications

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“…Experimentally, it has been found that the C5′• of dAdo or dGuo forms a bond with the C8 atom with a cyclization rate constant of 1.6 × 10 5 s −1 (Boussicault et al, 2008; Huang et al, 2011; Romieu et al, 1999). The C5′-C8 cycloguanine structure exists in two diastereoisomeric forms: (i) 5′(S),8-cyclo-2′-deoxyguanosin-7-yl and (ii) 5′ (R),8-cyclo-2′-deoxyguanosin-7-yl.…”

Section: Electron Reaction With Dnamentioning

confidence: 99%

Gamma and ion-beam irradiation of DNA: Free radical mechanisms, electron effects, and radiation chemical track structure

Sevilla

Becker

Kumar

et al. 2016

Radiation Physics and Chemistry

119

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The focus of our laboratory’s investigation is to study the direct-type DNA damage mechanisms resulting from γ-ray and ion-beam radiation-induced free radical processes in DNA which lead to molecular damage important to cellular survival. This work compares the results of low LET (γ−) and high LET (ion-beam) radiation to develop a chemical track structure model for ion-beam radiation damage to DNA. Recent studies on protonation states of cytosine cation radicals in the N1-substituted cytosine derivatives in their ground state and 5-methylcytosine cation radicals in ground as well as in excited state are described. Our results exhibit a radical signature of excitations in 5-methylcytosine cation radical. Moreover, our recent theoretical studies elucidate the role of electron-induced reactions (low energy electrons (LEE), presolvated electrons (epre−), and aqueous (or, solvated) electrons (eaq−)). Finally DFT calculations of the ionization potentials of various sugar radicals show the relative reactivity of these species.

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Section: Electron Reaction With Dnamentioning

confidence: 99%

Gamma and ion-beam irradiation of DNA: Free radical mechanisms, electron effects, and radiation chemical track structure

Sevilla

Becker

Kumar

et al. 2016

Radiation Physics and Chemistry

119

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“…TG is a helix-distorting lesion that causes the damaged base to assume an extrahelical position [35]; therefore, it poses a formidable block to DNA synthesis past the lesion [36]. The cPu lesion is caused by a second covalent bond between the base and corresponding sugar, which perturbs normal helix twist and base stacking [37, 38]. The cPu adduct interferes with replication [39] and transcription [40].…”

Section: Single Oxidative Base Lesions Differentially Affect Unwindinmentioning

confidence: 99%

Mechanistic and biological considerations of oxidatively damaged DNA for helicase-dependent pathways of nucleic acid metabolism

Crouch

Brosh

2017

Free Radical Biology and Medicine

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Cells are under constant assault from reactive oxygen species that occur endogenously or arise from environmental agents. An important consequence of such stress is the generation of oxidatively damaged DNA, which is represented by a wide range of non-helix distorting and helix-distorting bulkier lesions that potentially affect a number of pathways including replication and transcription; consequently DNA damage tolerance and repair pathways are elicited to help cells cope with the lesions. The cellular consequences and metabolism of oxidatively damaged DNA can be quite complex with a number of DNA metabolic proteins and pathways involved. Many of the responses to oxidative stress involve a specialized class of enzymes known as helicases, the topic of this review. Helicases are molecular motors that convert the energy of nucleoside triphosphate hydrolysis to unwinding of structured polynucleic acids. Helicases by their very nature play fundamentally important roles in DNA metabolism and are implicated in processes that suppress chromosomal instability, genetic disease, cancer, and aging. We will discuss the roles of helicases in response to nuclear and mitochondrial oxidative stress and how this important class of enzymes help cells cope with oxidatively generated DNA damage through their functions in the replication stress response, DNA repair, and transcriptional regulation.

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“…34 The S -cdG participates in Watson–Crick hydrogen bonding with the complementary dC. However, the S -cdG deoxyribose shifts to the O4′- exo pseudorotation with P = 280°.…”

Section: Introductionmentioning

confidence: 99%

Structures of (5′S)-8,5′-Cyclo-2′-deoxyguanosine Mismatched with dA or dT

Huang

Das

Basu

et al. 2012

Chem. Res. Toxicol.

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Diastereomeric 8,5′-cyclopurine 2′-deoxynucleosides, containing a covalent bond between the deoxyribose and the purine base, are induced in DNA by ionizing radiation. They are suspected to play a role in the etiology of neurodegeneration in xeroderma pigmentosum patients. If not repaired, the S-8,5′-cyclo-2′-deoxyguanosine lesion (S-cdG) induces Pol V-dependent mutations at a frequency of 34% in Escherichia coli. Most are S-cdG → A transitions, suggesting mis-incorporation of dTTP opposite the lesion during replication bypass, although low levels of S-cdG → T transversions, arising from mis-incorporation of dATP, are also observed. We report the structures of 5′-d(GTGCXTGTTTGT)-3′·5′-d(ACAAACAYGCAC)-3′, where X denotes S-cdG and Y denotes either dA or dT, corresponding to the situation following mis-insertion of either dTTP or dATP opposite the S-cdG lesion. The S-cdG·dT mismatch pair adopts a wobble base pairing. This provides a plausible rationale for the S-cdG → A transitions. The S-cdG·dA mismatch pair differs in conformation from the dG·dA mismatch pair. For the S-cdG·dA mismatch pair, both S-cdG and dA intercalate, but no hydrogen bonding is observed between S-cdG and dA. This is consistent with the lower levels of S-cdG → T transitions in E. coli.

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Structure of (5′S)-8,5′-Cyclo-2′-deoxyguanosine in DNA

Cited by 45 publications

References 83 publications

Gamma and ion-beam irradiation of DNA: Free radical mechanisms, electron effects, and radiation chemical track structure

Gamma and ion-beam irradiation of DNA: Free radical mechanisms, electron effects, and radiation chemical track structure

Mechanistic and biological considerations of oxidatively damaged DNA for helicase-dependent pathways of nucleic acid metabolism

Structures of (5′S)-8,5′-Cyclo-2′-deoxyguanosine Mismatched with dA or dT

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