Formation and Direct Repair of UV‐induced Dimeric DNA Pyrimidine Lesions

Abstract

Direct repair of UV-induced DNA lesions represents an elegant method for many organisms to deal with these highly mutagenic and cytotoxic compounds. Although the participating proteins are structurally well investigated, the exact repair mechanism of the photolyase enzymes remains a vivid subject of current research. In this review, we summarize and highlight the recent contributions to this exciting field.

Using UV-C radiation and image analysis for fungus control in tomato plants

“…In general, the data show that short exposure times of UV-C irradiation significantly reduced the growing rate of powdery mildew on greenhouse-grown tomato plants post natural infection by fungus, without negative effects on plant growth, which few times has been tested directly on whole plants, since almost all studies have been carried out on harvested plant products. Biologically, it is known that UV-C light has a direct effect on the pathogen by killing its mycelium [25], besides the absorption of high-energy UV photons by fungi DNA bases induces DNA damage provoking the conformation of dimers [43] that block the action of DNA polymerase and thereby prevent genome replication and cell cycle [4]. Inhibition of mitochondrial activity also occurs, which constrains cell wall biosynthesis, followed by impaired or reduced conidial germination [44].…”

EPR Study of UV-Irradiated Thymidine Microcrystals Supports Radical Intermediates in Spore Photoproduct Formation

“…This produced powdery white crystals of H/D-thy. The exchange in methanol-d4 appears complete as indicated by 1 H NMR ( Figure S8). The same procedure was used to prepare H/D-thy-d3 from thymidine-d3.…”

“…Although the pyrimidine bases have been observed to form different classes of dimers, including cyclobutane pyrimidine dimers and pyrimidine 6-4 pyrimidone photoproducts, 1 the SP, or 5-thyminyl-5,6-dihydrothymine (see Scheme 1) is the dominant photoproduct in bacterial endospore DNA. 2,3 A combination of the low hydration level of DNA, DNA saturation by small acid-soluble proteins, and a high calcium dipicolinate concentration in dormant endospores creates an environment that favors the A conformation of DNA and formation of the 5R enantiomer (due to DNA helical structure) of SP over other thymidine photoproducts.…”

Probing deactivation pathways of DNA nucleobases by two-dimensional electronic spectroscopy: first principles simulations

“…A thorough overview of the current status of research is given in several review articles [1][2][3][4] . Multimeric nucleobase systems formed through stacking (single-stranded DNA) and base-pairing (double-standed DNA) add many new facades to the photophysics of single bases: formation and dynamics of exciton states 5,6 , population and decay of intra-and inter-strand charge transfer (CT) excimer states 7,8 , charge separation and recombination [9][10][11] , ultrafast decay through photoinduced proton transfer 7,[12][13][14][15] , formation of lesions [16][17][18] . Interpretation of the electronic spectra of DNA multimers, which is the entirety of all these processes, is a challenge for the conventional one-dimensional (1D) pump-probe spectroscopy.…”