UVA irradiation of BrU-substituted DNA in the presence of Hoechst 33258.

Given that our knowledge of DNA repair is limited because of the complexity of the DNA system, a technique called UVA micro-irradiation has been developed that can be used to visualize the recruitment of DNA repair proteins at double-strand break (DSB) sites. Interestingly, Hoechst 33258 was used under micro-irradiation to sensitize 5-bromouracil (BrU)-labelled DNA, causing efficient DSBs. However, the molecular basis of DSB formation under UVA micro-irradiation remains unknown. Herein, we investigated the mechanism of DSB formation under UVA micro-irradiation conditions. Our results suggest that the generation of a uracil-5-yl radical through electron transfer from Hoechst 33258 to BrU caused DNA cleavage preferentially at self-complementary 5'-AABrUBrU-3' sequences to induce DSB. We also investigated the DNA cleavage in the context of the nucleosome to gain a better understanding of UVA micro-irradiation in a cell-like model. We found that DNA cleavage occurred in both core and linker DNA regions although its efficiency reduced in core DNA. Copyright © 2017 Elsevier Ltd. All rights reserved.

Citation

Abhijit Saha, Seiichiro Kizaki, Ji Hoon Han, Zutao Yu, Hiroshi Sugiyama. UVA irradiation of BrU-substituted DNA in the presence of Hoechst 33258. Bioorganic & medicinal chemistry. 2017 Nov 06

PMID: 29170027

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