Open AccessHuman nucleotide excision nuclease removes thymine dimers from DNA by incising the 22nd phosphodiester bond 5' and the 6th phosphodiester bond 3' to the photodimer.
Author(s) -
Juch-Chin Huang,
Daniel Svoboda,
Joyce T. Reardon,
Aziz Sancar
Publication year - 1992
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.89.8.3664
Subject(s) - phosphodiester bond , exonuclease , thymidine , nuclease , dna , pyrimidine dimer , nucleotide , chemistry , nucleotide excision repair , thymine , microbiology and biotechnology , biochemistry , biology , dna repair , rna , dna polymerase , gene
By using a human cell-free system capable of nucleotide excision repair, a synthetic substrate consisting of a plasmid containing four thymidine dimers at unique locations, and deoxyribonucleoside 5'-[alpha-thio]triphosphates for repair synthesis, we obtained DNA fragments containing repair patches with phosphorothioate linkages. Based on the resistance of these linkages to digestion by exonuclease III and their sensitivity to cleavage by I2, we were able to delineate the borders of the repair patch to single-nucleotide resolution and found an asymmetric patch with sharp boundaries. That the repair patch was produced by filling in a gap generated by an excision nuclease and not by nick-translation was confirmed by the finding that the thymidine dimer was released in a 27- to 29-nucleotide oligomer.