Site-specific DNA transesterification by vaccinia topoisomerase: Effects of benzo[a]pyrene-dA, 8-oxoguanine, 8-oxoadenine, and 2-aminopurine modifications Journal Article
| Authors: | Yakovleva, L.; Tian, L.; Sayer, J. M.; Kalena, G. P.; Kroth, H.; Jerina, D. M.; Shuman, S. |
| Article Title: | Site-specific DNA transesterification by vaccinia topoisomerase: Effects of benzo[a]pyrene-dA, 8-oxoguanine, 8-oxoadenine, and 2-aminopurine modifications |
| Abstract: | Vaccinia DNA topoisomerase forms a covalent DNA-(3′ -phosphotyrosyl)-enzyme intermediate at a specific target site 5′-C +5C+4C+3T+2T+1p ↓ N-1 in duplex DNA. Here we study the effects of base modifications on the rate and extent of single-turnover DNA transesterification. Chiral trans opened C-10 R and S adducts of benzo[a]pyrene (BP) 7,8-diol 9,10-epoxide were introduced at single N6-deoxyadenosine (dA) positions within the 3′-G+5G+4G+3A+2A +1T-1A-2 sequence of the nonscissile DNA strand. The R and S BPdA adducts intercalate from the major groove on the 5′ and 3′ sides of the modified base, respectively, and perturb local base stacking. We found that R and S BPdA modifications at +1A reduced the transesterification rate by a factor of 700-1000 without affecting the yield of the covalent topoisomerase-DNA complex. BPdA modifications at +2A reduced the extent of transesterification and elicited rate decrements of 200- and 7000-fold for the S and R diastereomers, respectively. In contrast, BPdA adducts at the -2 position had no effect on the extent of the reaction and relatively little impact on the rate of cleavage. A more subtle probe of major groove contacts entailed substituting each of the purines of the nonscissile strand with its 8-oxo analog. The +3 oxoG modification slowed transesterification 35-fold, whereas other 8-oxo modifications were benign. 8-Oxo substitutions at the -1 position in the scissile strand slowed single-turnover cleavage by a factor of six but had an even greater slowing effect on religation, which resulted in an increase in the cleavage equilibrium constant. 2-Aminopurine at positions +3, +4, or +5 in the nonscissile strand had no effect on transesterification per se but had synergistic effects when combined with 8-oxoA at position -1 in the scissile strand. These findings illuminate the functional interface of vaccinia topoisomerase with the DNA major groove. |
| Keywords: | unclassified drug; nonhuman; dna; dna modification; kinetics; dna viruses; guanosine; nucleotide sequence; vaccinia virus; base sequence; benzo[a]pyrene; dna sequence; dna adducts; models, molecular; binding sites; esterification; purine derivative; enzyme kinetics; nucleic acid conformation; chelating agents; transesterification; stereoisomerism; dna topoisomerase; 8 hydroxyguanine; reaction time; reduction; virus dna; chirality; dna strand; dna protein complex; covalent bond; epoxide; dna topoisomerases; 7,8-dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide; adenine derivative; deoxyadenosine derivative; aromatic compounds; substitution reactions; 2 aminopurine; priority journal; article; staphylococcus phage 3a; dna base; transesterifications; 7,8 dihydroxybenzo[a]pyrene 9,10 oxide; 8 oxoadenine; n6 deoxyadenosine |
| Journal Title: | Journal of Biological Chemistry |
| Volume: | 278 |
| Issue: | 43 |
| ISSN: | 0021-9258 |
| Publisher: | American Society for Biochemistry and Molecular Biology |
| Date Published: | 2003-10-24 |
| Start Page: | 42170 |
| End Page: | 42177 |
| Language: | English |
| DOI: | 10.1074/jbc.M308079200 |
| PUBMED: | 12909623 |
| PROVIDER: | scopus |
| DOI/URL: | |
| Notes: | Export Date: 12 September 2014 -- Source: Scopus |
Altmetric
Citation Impact
BMJ Impact Analytics
Related MSK Work