Intercalating polycyclic aromatic hydrocarbon-DNA adducts poison DNA religation by vaccinia topoisomerase and act as roadblocks to digestion by exonuclease III Journal Article
| Authors: | Yakovleva, L.; Handy, C. J.; Yagi, H.; Sayer, J. M.; Jerina, D. M.; Shuman, S. |
| Article Title: | Intercalating polycyclic aromatic hydrocarbon-DNA adducts poison DNA religation by vaccinia topoisomerase and act as roadblocks to digestion by exonuclease III |
| Abstract: | Polycyclic aromatic hydrocarbon (PAH)-DNA adducts pervert the execution or fidelity of enzymatic DNA transactions and cause mutations and cancer. Here, we examine the effects of intercalating PAH-DNA adducts on the religation reaction of vaccinia DNA topoisomerase, a prototypal type IB topoisomerase (TopIB), and the 3′ end-resection reaction of Escherichia coli exonuclease III (ExoIII), a DNA repair enzyme. Vaccinia TopIB forms a covalent DNA-(3′-phosphotyrosyl)-enzyme intermediate at a target site 5′-C+5C+4C+3T+2T +1p↓N-1 in duplex DNA. The rate of the forward cleavage reaction is suppressed to varying degrees by benzo[a]pyrene (BP) or benzo[c]phenanthrene (BPh) adducts at purine bases within the 3′-G +5G+4G+3A+2A+1T -1A-2 sequence of the nonscissile strand. We report that BP adducts at the +1 and -2 N6-deoxyadenosine (dA) positions flanking the scissile phosphodiester slow the rate of DNA religation to a greater degree than they do the cleavage rate. By increasing the cleavage equilibrium constant ≥10-fold, the BPdA adducts, which are intercalated via the major groove, act as TopIB poisons. With respect to ExoIII, we find that (i) single BPdA adducts act as durable roadblocks to ExoIII digestion, which is halted at sites 1 and 2 nucleotides prior to the modified base; (ii) single BPhdA adducts, which also intercalate via the major groove, elicit a transient pause prior to the lesion, which is eventually resected; and (iii) BPh adducts at N2- deoxyguanosine, which intercalate via the minor groove, are durable impediments to ExoIII digestion. These results highlight the sensitivity of repair outcomes to the structure of the PAH ring system and whether intercalation occurs via the major or minor groove. © 2006 American Chemical Society. |
| Keywords: | mutation; dna damage; dna repair; protein dna binding; dna; double stranded dna; kinetics; tumors; escherichia coli; substrate specificity; vaccinia virus; base sequence; benzo[a]pyrene; dna adduct; dna adducts; binding sites; nucleic acid conformation; mutagenesis; enzymes; dna topoisomerase; polycyclic hydrocarbons, aromatic; dna degradation; exodeoxyribonucleases; purine; nucleotides; polycyclic aromatic hydrocarbon; intercalation complex; virus enzyme; reaction kinetics; dna topoisomerases; equilibrium constant; intercalation compounds; cleavage reaction; religation reaction; polycyclic aromatic hydrocarbons; deoxyadenosine; exodeoxyribonuclease iii; dna religation; intercalating agents |
| Journal Title: | Biochemistry |
| Volume: | 45 |
| Issue: | 24 |
| ISSN: | 0006-2960 |
| Publisher: | American Chemical Society |
| Date Published: | 2006-06-20 |
| Start Page: | 7644 |
| End Page: | 7653 |
| Language: | English |
| DOI: | 10.1021/bi060158h |
| PUBMED: | 16768460 |
| PROVIDER: | scopus |
| DOI/URL: | |
| Notes: | --- - "Cited By (since 1996): 9" - "Export Date: 4 June 2012" - "CODEN: BICHA" - "Source: Scopus" |
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