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Updated: Jul 19, 2026

Advanced Confocal Microscopy Techniques to Study Protein-protein Interactions and Kinetics at DNA Lesions
Published on: November 12, 2017
Low ionic strength reduces cytosine photoreactivity in UVC-irradiated isolated DNA
1Laboratoire Lésions des Acides Nucléiques, Service de Chimie Inorganique et Biologique UMR-E 3 CEA-UJF, CEA/DSM/Département de Recherche Fondamentale sur la Matière Condensée, CEA-Grenoble, 38054, Grenoble Cedex 9, France. thierry.douki@cea.fr
Abstract:
Exposure of DNA to far-UV radiation leads to the formation of several types of dimeric lesions, including cyclobutane dimers and (6-4) photoproducts. In order to gain insights into the main parameters driving DNA photochemistry, the effect of ionic strength on the yield of formation of these photoproducts was investigated in UVC-irradiated samples of isolated genomic DNA. The main consequence of lowering the ionic strength was a decrease in the UVC-induced formation of thymine-cytosine and cytosine-cytosine photoproducts. The reactivity of thymine-thymine and cytosine-thymine doublets was hardly affected. Evidence was obtained against a major role played by duplex denaturation in these observations. A more likely explanation is a change in the DNA structure as the result of a larger extent of protonation at low counter-ions concentration.
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