## Abstract Topotecan (TPT), a waterโsoluble derivative of camptothecin, is a potent antitumor poison of human DNA topoisomerase I (top1) that stabilizes the cleavage complex between the enzyme and DNA. The role of the recently discovered TPT affinity to DNA remains to be defined. The aim of this w
Trapping of human DNA topoisomerase I by DNA structures mimicking intermediates of DNA repair
โ Scribed by Natalia Lebedeva; Nadejda Rechkunova; Serge Boiteux; Olga Lavrik
- Publisher
- John Wiley and Sons
- Year
- 2008
- Tongue
- English
- Weight
- 161 KB
- Volume
- 60
- Category
- Article
- ISSN
- 1521-6543
- DOI
- 10.1002/iub.5
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โฆ Synopsis
Abstract
In this report we show that human DNA Topoisomerase I (Top1) forms DNAโprotein adducts with nicked and gapped DNA structures lacking a conventional Top1 cleavage site. The radioactively labeled crosslinking products were identified by SDSโgel electrophoresis. The chemical structure of the groups at 5โฒ or 3โฒ end of the nick does not have an effect on the formation of these covalent adducts. Therefore, all kinds of nicks, either directly induced by ionizing radiation or reactive oxygen species or indirectly induced in the course of base excision repair (BER) are targets for Top1 that competes with BER proteins and other nickโsensors. Top1โDNA covalent adducts formed in cells exposed to DNA damaging agents can promote genetic instability. ยฉ 2008 IUBMB IUBMB Life, 60(2): 130โ134, 2008
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