title: Structural insights by molecular dynamics simulations into specificity of the major human AP endonuclease toward the benzene-derived DNA adduct, pBQ-C.
abstract: The benzetheno exocyclic adduct of the cytosine (C) base (pBQ-C) is a product of reaction between DNA and a stable metabolite of the human carcinogen benzene, p-benzoquinone (pBQ). We reported previously that the pBQ-C-containing duplex is a substrate for the human AP endonuclease (APE1), an enzyme that cleaves an apurinic/apyrimidinic (AP) site from double stranded DNA. In this work, using molecular dynamics simulation (MD), we provided a structural explanation for the recognition of the pBQ-C adduct by APE1. Molecular modeling of the DNA duplex containing pBQ-C revealed significant displacement of this adduct toward the major groove with pronounced kinking of the DNA at the lesion site, which could serve as a structural element recognized by the APE1 enzyme. Using 3 ns MD it was shown that the position of the pBQ-C adduct is stabilized by two hydrogen bonds formed between the adduct and the active site amino acids Asp 189 and Ala 175. The pBQ-C/APE1 complex, generated by MD, has a similar hydrogen bond network between target phosphodiester bond at the pBQ-C site and key amino acids at the active site, as in the crystallographically determined APE1 complexed with an AP site-containing DNA duplex. The position of the adduct at the enzyme active site, together with the hydrogen bond network, suggests a similar reaction mechanism for phosphodiester bond cleavage of oligonucleotide containing pBQ-C as reported for the AP site.
authors.affiliation: Donner Laboratory, Life Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720, USA.
authors.forename: Anton B
authors.initials: AB
authors.lastname: Guliaev
authors.forename: Bo
authors.initials: B
authors.lastname: Hang
authors.forename: B
authors.initials: B
authors.lastname: Singer
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D003198:Computer Simulation; D018736:DNA Adducts / Q000737:chemistry* / Q000378:metabolism; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D013379:Substrate Specificity
chemical_list: D018736:DNA Adducts; C487771:pBQ-dC adduct; C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase