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  • The EMBO Journal (2007) 26, 2923 - 2932
  • doi:10.1038/sj.emboj.7601730

Published online: 24 May 2007

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

Vincent Mocquet1, Konstantin Kropachev2, Marina Kolbanovskiy2, Alexander Kolbanovskiy2, Angels Tapias1, Yuqin Cai2, Suse Broyde3, Nicholas E Geacintov2 and Jean-Marc Egly1

  1. Chemistry Department, Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, Strasbourg, France
  2. Chemistry Department, New York University, New York, NY, USA
  3. Biology Department, New York University, New York, NY, USA

Correspondence to:

Nicholas E GeacintovJean-Marc Egly, Chemistry Department, New York University, 31 Washington Place, New York, NY 10003-5180, USA. Tel.: +1 212 998 8407; Fax: +1 212 998 8421; E-mail: ng1@nyu.edu

Received 23 September 2006; Accepted 30 April 2007

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.

  • Keywords:

    • benzo[a]pyrene,
    • cisplatin,
    • DNA repair,
    • NER,
    • XPC