Photorepair Processes

Eker, A.P.M.

doi:10.1007/978-1-4757-0896-7_8

Cited by 17 publications

(9 citation statements)

References 120 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Photolyases characterized thus far appear to fall into two classes with respect to their essential chromophores (6). All photolyases appear to contain flavin adenine dinucleotide.…”

Section: Wave-length Dependence Of Photoreactivation Crosssection Of mentioning

confidence: 99%

UV-B-Inducible and Temperature-Sensitive Photoreactivation of Cyclobutane Pyrimidine Dimers in Arabidopsis thaliana

Pang

Hays²

1991

Plant Physiol.

252

171

View full text Add to dashboard Cite

Removal of cyclobutane pyrimidine dimers (CBPDs) in vivo from the DNA of UV-irradiated eight-leaf seedlings of Arabidopsis thaliana was rapid in the presence of visible light (half-life about 1 hour); removal of CBPDs in the dark, presumably via excision repair, was an order of magnitude slower. Extracts of plants contained significant photolyase in vitro, as assayed by restoration of transforming activity to UV-irradiated Escherichia coii plasmids; activity was maximal from four-leaf to 12-leaf stages. UV-B treatment of seedlings for 6 hours increased photolyase specific activity in extracts twofold. Arabidopsis photolyase was markedly temperature-sensitive, both in vitro (half-life at 300C about 12 minutes) and in vivo (half-life at 300C, 30 to 45 minutes).The wavelength dependency of the photoreactivation cross-section showed a broad peak at 375 to 400 nm, and is thus similar to that for maize pollen; it overlaps bacterial and yeast photolyase action spectra.Stratospheric ozone depletion projected for the early 21st century is expected to increase the amount of DNA-damaging UV-B (290-320 nm) radiation at the earth's surface by as much as 20 to 50% (2, 10, 33). This has renewed interest in the UV-resistance mechanisms of plants, which will be exposed continually to increased UV-B fluxes.Repair of ultraviolet-light-induced DNA damage is a feature of life at all levels of complexity. Studies of bacteria (particularly Escherichia coli), yeast, and mammalian cells have elucidated four distinct mechanisms by which cells cope with UV-damaged DNA (for reviews see refs. 9, 29). In photoreactivation, a single enzyme, photolyase, uses light energy in the 300 to 500 nm range to reverse a specific class of UV photoproducts-cis, syn CBPDs.2 In excision repair, an ensemble of proteins act together to remove a wide variety of helix-distorting lesions, including at least two UV photoproducts-CBPDs and pyrimidine-(6-4)-pyrimidone photoproducts (6-4 photoproducts). Photoproducts that block DNA replication are tolerated, rather than repaired,

show abstract

“…Photolyases characterized thus far appear to fall into two classes with respect to their essential chromophores (6). All photolyases appear to contain flavin adenine dinucleotide.…”

Section: Wave-length Dependence Of Photoreactivation Crosssection Of mentioning

confidence: 99%

UV-B-Inducible and Temperature-Sensitive Photoreactivation of Cyclobutane Pyrimidine Dimers in Arabidopsis thaliana

Pang

Hays²

1991

Plant Physiol.

252

171

View full text Add to dashboard Cite

show abstract

“…The wavelength and the shape of the main peak are quite similar to those obtained with H . cutirubrum (Eker, 1983).…”

Section: Action Spectrum Of Photoreactivationmentioning

confidence: 99%

“…According to Eker (1983), the action spectrum of photoreactivation is divided into two groups; in one group photoreactivation efficiencies at 440 nm are 4 times greater than those at 370 nm, while in the second group the ratio of 440 nm to 370 nm efficiencies is less than 1. Streptomyces is the typical example of the former case (Eker et al, 1981).…”

Section: Action Spectrum Of Photoreactivationmentioning

confidence: 99%

PHOTOREACTIVATION OF Halobacterium halobium: ACTION SPECTRUM AND ROLE OF PIGMENTATION

Iwasa

Tokutomi

Tokunaga

1988

Photochem & Photobiology

View full text Add to dashboard Cite

Abstract— An action spectrum for photoreactivation was measured with Halobacterium halobium R1m1 to prove a role of carotenoid pigments in photoreactivation of the bacteria. The action spectrum obtained showed a main peak at 435 nm and a minor peak at about 325 nm. The action spectrum was similar to that of Streptomyces pigment (Eker et al., 1981) suggesting that the chromophore of the photoreactivating enzyme in Halobacterium halobium is 8‐OH‐5‐deazaflavin. The minor peak may be due to photochemical cleavage of a pyrimidine6–4 hetero adduct. The result indicates that carotenoid pigments do not play a positive role in enhancing photoreactivation. This was confirmed also by comparing the efficiency of photoreactivation at 465 nm among three strains of Halobacterium halobium having different carotenoid pigments; R1m1. R1 and W5002–1.

show abstract

“…Both the %oGC bias in codons and the excess of acidic amino acids in the deduced amino acid sequence are characteristic for a halobacterial gene. While the optimal ionic strength ranges from 0.04 to 0.18 for PRE from non-halobacterial organisms (Eker, 1983), optimal activity was found at 1 M NaCl for H . cutirubnun PRE (Fig.…”

Section: H Cutirubrum Photoreactivating Enzymementioning

confidence: 99%

“…In the present study UV-inactivation and photoreactivation experiments with pigmented and colorless H. cutirubrum isolates are reported to determine the influence of carotenoids and gas vesicles. In addition to a preliminary action spectrum of photoreactivation already published (Eker, 1983), a high resolution action spectrum is presented to establish the type of photoreactivating enzyme in H. cutirubrum.…”

Section: Introductionmentioning

confidence: 99%

PHOTOREACTIVATION IN THE EXTREME HALOPHILIC ARCHAEBACTERIUM Halobacterium cutirubrum

Eker¹,

Formenoy²,

Wit³

1991

Photochem Photobiol

Self Cite

View full text Add to dashboard Cite

Photoreactivation in the extreme halophilic archaebacterium Halobacterium cutirubrum was studied both in vivo and in v i m . Cells irradiated with ultraviolet (UV)-fluences up to 350 JimZ could be completely photoreactivated, indicating very efficient repair of pyrimidine dimers in UV-irradiated DNA. Dark repair is apparently absent in Halobacterium since liquid holding under non-growth conditions did not influence the survival of UV-irradiated cells, while cells remained completely photoreactivable with no change in the kinetics of photoreactivation. Experiments with Halobacterium isolates of different carotenoid content indicated that carotenoids do not influence either UV-inactivation or photoreactivation. Small differences in the rates of UV-inactivation and photoreactivation could be assigned to the occurrence of gas vesicles. Flash experiments and the temperature dependence of photoreactivation indicated an enzymatical reaction. This was confirmed by in vitro experiments with partially purified photoreactivating enzyme. The in vivo action spectrum of photoreactivation showed a main band in the 400470 nm region with a maximum at 440 nm. Comparison with action spectra of other microorganisms classified the Halobacterium enzyme as a 8-hydroxy-5-deazaflavin type photoreactivating enzyme.

show abstract

Photorepair Processes

Cited by 17 publications

References 120 publications

UV-B-Inducible and Temperature-Sensitive Photoreactivation of Cyclobutane Pyrimidine Dimers in Arabidopsis thaliana

UV-B-Inducible and Temperature-Sensitive Photoreactivation of Cyclobutane Pyrimidine Dimers in Arabidopsis thaliana

PHOTOREACTIVATION OF Halobacterium halobium: ACTION SPECTRUM AND ROLE OF PIGMENTATION

PHOTOREACTIVATION IN THE EXTREME HALOPHILIC ARCHAEBACTERIUM Halobacterium cutirubrum

Contact Info

Product

Resources

About