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Trapping of human DNA topoisomerase I by DNA structures mimicking intermediates of DNA repair
Author(s) -
Lebedeva Natalia,
Rechkunova Nadejda,
Boiteux Serge,
Lavrik Olga
Publication year - 2008
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1002/iub.5
Subject(s) - dna , topoisomerase , adduct , covalent bond , chemistry , cleavage (geology) , dna damage , base excision repair , base pair , dna repair , gel electrophoresis , microbiology and biotechnology , biochemistry , biology , paleontology , organic chemistry , fracture (geology)
In this report we show that human DNA Topoisomerase I (Top1) forms DNA‐protein adducts with nicked and gapped DNA structures lacking a conventional Top1 cleavage site. The radioactively labeled crosslinking products were identified by SDS‐gel electrophoresis. The chemical structure of the groups at 5′ or 3′ 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 nick‐sensors. Top1‐DNA covalent adducts formed in cells exposed to DNA damaging agents can promote genetic instability. © 2008 IUBMB IUBMB Life, 60(2): 130–134, 2008