Abstract
To evaluate the structural influence of the DNA phosphate backbone on the activity of Escherichia coli DNA topoisomerase I, modified forms of oligonucleotide dA7 were synthesized with a chiral phosphorothioate replacing the non-bridging oxygens at each position along the backbone. A deoxy-iodo-uracil replaced the 5′-base to crosslink the oligonucleotides by ultraviolet (UV) and assess binding affinity. At the scissile phosphate there was little effect on the cleavage rate. At the +1 phosphate, the rectus phosphorus (Rp)-thio-substitution reduced the rate of cleavage by a factor of 10. At the +3 and -2 positions from the scissile bond, the Rp-isomer was cleaved at a faster rate than the sinister phosphorus (Sp)-isomer. The results demonstrate the importance of backbone contacts between DNA substrate and E. coli topoisomerase I.
Original language | English (US) |
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Pages (from-to) | 175-180 |
Number of pages | 6 |
Journal | International Journal of Biological Macromolecules |
Volume | 29 |
Issue number | 3 |
DOIs | |
State | Published - Oct 22 2001 |
Externally published | Yes |
Keywords
- DNA cleavage
- Phosphorothioate
- Topoisomerase I
ASJC Scopus subject areas
- Structural Biology
- Biochemistry
- Molecular Biology
- Economics and Econometrics
- General Energy