The human DNA repair factor XPC-HR23B distinguishes stereoisomeric benzo[a]pyrenyl-DNA lesions

Vincent Mocquet, Konstantin Kropachev, Marina Kolbanovskiy, Alexander Kolbanovskiy, Angels Tapias, Yuqin Cai, Suse Broyde, Nicholas E. Geacintov, Jean Marc Egly

Research output: Contribution to journalArticlepeer-review


Benzo[a]pyrene (B[a]P), a known environmental pollutant and tobacco smoke carcinogen, is metabolically activated to highly tumorigenic B[a]P diol epoxide derivatives that predominantly form N2-guanine adducts in cellular DNA. Although nucleotide excision repair (NER) is an important cellular defense mechanism, the molecular basis of recognition of these bulky lesions is poorly understood. In order to investigate the effects of DNA adduct structure on NER, three stereoisomeric and conformationally different B[a]P-N2-dG lesions were site specifically incorporated into identical 135-mer duplexes and their response to purified NER factors was investigated. Using a permanganate footprinting assay, the NER lesion recognition factor XPC/HR23B exhibits, in each case, remarkably different patterns of helix opening that is also markedly distinct in the case of an intra-strand crosslinked cisplatin adduct. The different extents of helix distortions, as well as differences in the overall binding of XPC/HR23B to double-stranded DNA containing either of the three stereoisomeric B[a]P-N2-dG lesions, are correlated with dual incisions catalyzed by a reconstituted incision system of six purified NER factors, and by the full NER apparatus in cell-free nuclear extracts.

Original languageEnglish (US)
Pages (from-to)2923-2932
Number of pages10
JournalEMBO Journal
Issue number12
StatePublished - Jun 20 2007


  • Benzo[a]pyrene
  • Cisplatin
  • DNA repair
  • NER
  • XPC

ASJC Scopus subject areas

  • General Neuroscience
  • Molecular Biology
  • General Biochemistry, Genetics and Molecular Biology
  • General Immunology and Microbiology


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