PHOTOPRODUCTS IN DNA IRRADIATED <i>IN VIVO</i>*

Setlow, R. B.

doi:10.1111/j.1751-1097.1968.tb08047.x

Cited by 54 publications

(8 citation statements)

References 18 publications

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“…With this solvent, photoproduct I11 migrates with an Rf =0.21, which shows it cannot be due to the cytosine-thymine (C-'I') adduct or the 'spore' photoproduct (Donnellan and Setlow, 1965). The mixed dimer U <> T, derived from C <> T during hydrolysis, can also be eliminated, because it appears when DNA is photosensitized by acetophenone (5 per cent of the total dimer yield: Ben-Ishai et al., 1968;Lamola, 1969) as well as by direct irradiation, with a yield much larger than in our experiments (33 per cent of the total dimer yield: Setlow and Carrier, 1966). Peak I1 is probably a mixture of T <> T and U <> T cyclobutanetype dimers (and may be C-T adducts, which migrate with the same Rf as T <> T in acidic solvents; Varghese and Wang, 1967).…”

Section: Photoproducts Produced In Dna By Uv Irradiationmentioning

confidence: 99%

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Photosensitized Splitting of Pyrimidine Dimers in Dna by Indole Derivatives and Tryptophan‐containing Peptides

Charlier

Hélène

1975

Photochem & Photobiology

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Abstract—Indole derivatives, such as serotonin or the oligopeptide Lys‐Trp‐Lys, are able to photosensitize the splitting of thymine dimers in DNA. These indole derivatives have to be bound to DNA in order to efficiently photosensitize the splitting reaction. Serotonin may also induce the photosensitized formation of thymine‐containing dimers in native DNA. In this case, an equilibrium is reached when 5 per cent of the total thymines are dimerized. In both cases (splitting and dimer formation), the formation of electron donor‐acceptor complexes between either dimers or two adjacent thymine monomers, and excited indole rings, could be an intermediate step in the reactions. Thymine‐dimer splitting would then result from an electron transfer reaction involving the indole ring as the electron donor. These results are discussed with respect to the mechanism of action of the photoreactivating enzyme.

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Section: Photoproducts Produced In Dna By Uv Irradiationmentioning

confidence: 99%

“…UV irradiation of DNA at room temperature produces several types of damage, among which pyrimidine dimers appear to have the main biological importance (R. B. Setlow, 1968). These dimers can be split by short wavelength radiation (254 nm) Carrier, 1963 and or by enzymatic photoreactivation J.…”

Section: Introductionmentioning

confidence: 99%

Photosensitized Splitting of Pyrimidine Dimers in Dna by Indole Derivatives and Tryptophan‐containing Peptides

Charlier

Hélène

1975

Photochem & Photobiology

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“…photoproducts of principal biological significance in Escherichia coli are pyrimidine dimers in DNA which interfere with normal DNA replication, and may lead to cell death (Setlow, 1968).…”

Section: Introductionmentioning

confidence: 99%

Effects of Coumarin, Pyronin Y, 6,9-Dimethyl 2-Methylthiopurine and Caffeine on Excision Repair and Recombination Repair in Escherichia coli

Grigg

1972

Journal of General Microbiology

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S U M M A R YPyronin Y (0.06 and 0.16 mM), coumarin (2 and 4 mM), 6,pdimethyl 2-methylthiopurine (2 mM) and caffeine (8 m), strongly inhibit Uvr repair (presumed excision repair) of U.V. lesions in Escherichia coli. With 0.16 m-pyronin Y or 4m~-coumarin, one thymine dimer was a lethal event in the ~1 2 strain ~~2 9 2 6 rec A-13 and one to three dimers in the B/r derivative WP-2 rec A-13 and the B exr A derivative BS-2. Neither these compounds nor 8 mwcaffeine had a significant effect on the survival of irradiated bacteria of the corresponding uvr strains WP-2 Hcr-, BS-12, and BS-8. 1 suggest that 8 mM-caffeine, 0-16 mM-pyronin Y, 4 mM-coumarin and 2 m-6,9-dimethyl 2-methylthiopurine selectively block excision repair without substantially affecting recombination repair.Caffeine at 12 mM only slightly depressed the viability of a u.v.-irradiated culture of WP-2 Hcr-or BS-12, but at 16 mM there was a much greater effect, particularly at low U.V. doses ( < 40 ergs/mm2). Since excision repair appeared to be effectively blocked by 8 m-caffeine, the depression of U.V. survival of the uvr mutants by I 6 mM-Caffeine was presumed to be due to interference with recombination repair (Witkin & Farquharson, I 969). I N T R O D U C T I O NThe ultraviolet (u.v.) photoproducts of principal biological significance in Escherichia coli are pyrimidine dimers in DNA which interfere with normal DNA replication, and may lead to cell death (Setlow, 1968).Escherichia coli can cope with these lesions in the dark in at least two ways. In one, passage of the replicating fork past pyrimidine dimers in a priming strand results in a series of gaps in the freshly replicated strand, presumably because the dimers are unable to direct the insertion of nucleotides into the growing polynucleotide. The existence of discontinuities in the latter is thought to initiate recombination between daughter DNA strands permitting the reconstruction of the strands (Rupp & Howard-Flanders, 1968). This is referred to as ' recombination repair '. Two genes with alleles giving an impaired recombination repair effectiveness are rec A-13 and exr A . The other dark repair system involves the excision of pyrimidine dimers from the DNA and is termed excision repair. UVP Mutants are defective in this function.Some years ago caffeine (5 to 10 ITIM) was shown to inhibit dark repair (Witkin, 1958), and more recently excision repair (Setlow & Carrier, 1968). In vitro it neither inhibits DNA polymerase I activity (at a concentration of up to TOO mM, Grigg, 1968) (Kelly, Atkinson, Huberman & Kornberg, 1969). A number of factors other than caffeine interfere with dimer excision. These include crystal violet, acriflavine (Feiner & Hill, 1963;Setlow, 1964) cyanide, and starvation (Setlow & Carrier, 1968).The exact effects of caffeine on recombination repair are less obvious. Caffeine < 10.7 mM had very little effect on the U.V. survival of the uvr A mutant WP-2 Hcr-, which implies that the independent recombination-repair pathway was unaffected (Sideropoulos & Shankel, 1968;Wi...

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“…THE TRIPLET-STATE sensitization method can be used to produce thymine dimers [1,2], a major product of the irradiation of DNA with ultraviolet light (u.v.) [3]. The mechanism involves excitation of an appropriate sensitizer, in solution with DNA at wavelengths longer than the DNA absorption band.…”

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confidence: 99%

SENSITIZED PHOTOINACTIVATION OF BACTERIOPHAGE T4

Meistrich¹,

Lamola²,

Gabbay

1970

Photochem & Photobiology

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Abstract— The photoinactivation of an osmotic shock resistant mutant of the bacteriophage T4 can be sensitized by two cationic derivatives of acetophenone. At least part of the sensitized inactivation appears to be due to the formation of thymine dimers in phage DNA by a mechanism which involves triplet excitation transfer from the sensitizer to thymine in the DNA. The photoreactivable sector of the phage inactivated by sensitized irradiation is about 0.6, almost twice as large as the sector for u.v. irradiated phage.

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PHOTOPRODUCTS IN DNA IRRADIATED *IN VIVO**

Cited by 54 publications

References 18 publications

Photosensitized Splitting of Pyrimidine Dimers in Dna by Indole Derivatives and Tryptophan‐containing Peptides

Photosensitized Splitting of Pyrimidine Dimers in Dna by Indole Derivatives and Tryptophan‐containing Peptides

Effects of Coumarin, Pyronin Y, 6,9-Dimethyl 2-Methylthiopurine and Caffeine on Excision Repair and Recombination Repair in Escherichia coli

SENSITIZED PHOTOINACTIVATION OF BACTERIOPHAGE T4

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PHOTOPRODUCTS IN DNA IRRADIATED IN VIVO*

Cited by 54 publications

References 18 publications

Photosensitized Splitting of Pyrimidine Dimers in Dna by Indole Derivatives and Tryptophan‐containing Peptides

Photosensitized Splitting of Pyrimidine Dimers in Dna by Indole Derivatives and Tryptophan‐containing Peptides

Effects of Coumarin, Pyronin Y, 6,9-Dimethyl 2-Methylthiopurine and Caffeine on Excision Repair and Recombination Repair in Escherichia coli

SENSITIZED PHOTOINACTIVATION OF BACTERIOPHAGE T4

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PHOTOPRODUCTS IN DNA IRRADIATED *IN VIVO**