Open AccessInitiation of DNA Interstrand Cross-Link Repair in Humans: the Nucleotide Excision Repair System Makes Dual Incisions 5′ to the Cross-linked Base and Removes a 22- to 28-Nucleotide-long Damage-Free Strand
Author(s) -
Tadayoshi Bessho,
David Mu,
Aziz Sancar
Publication year - 1997
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.17.12.6822
Subject(s) - nucleotide excision repair , biology , nucleotide , nuclease , dna , duplex (building) , dna repair , base excision repair , dna damage , base pair , microbiology and biotechnology , genetics , gene
Most DNA repair mechanisms rely on the redundant information inherent to the duplex to remove damaged nucleotides and replace them with normal ones, using the complementary strand as a template. Interstrand cross-links pose a unique challenge to the DNA repair machinery because both strands are damaged. To study the repair of interstrand cross-links by mammalian cells, we tested the activities of cell extracts of wild-type or excision repair-defective rodent cell lines and of purified human excision nuclease on a duplex with a site-specific cross-link. We found that in contrast to monoadducts, which are removed by dual incisions bracketing the lesion, the cross-link causes dual incisions, both 5' to the cross-link in one of the two strands. The net result is the generation of a 22- to 28-nucleotide-long gap immediately 5' to the cross-link. This gap may act as a recombinogenic signal to initiate cross-link removal.