| Autor: |
Bhaduri, Tisha, Basak, Shashwati, Sikder, Devanjan, Nagaraja, Valakunja |
| Zdroj: |
FEBS Letters; December 2000, Vol. 486 Issue: 2 p126-130, 5p |
| Abstrakt: |
DNA topoisomerase I from Mycobacterium smegmatisunlike many other type I topoisomerases is a site specific DNA binding protein. We have investigated the sequence specific DNA binding characteristics of the enzyme using specific oligonucleotides of varied length. DNA binding, oligonucleotide competition and covalent complex assays show that the substrate length requirement for interaction is much longer (∼20 nucleotides) in contrast to short length substrates (eight nucleotides) reported for Escherichia colitopoisomerase I and III. P1 nuclease and KMnO4footprinting experiments indicate a large protected region spanning about 20 nucleotides upstream and 2–3 nucleotides downstream of the cleavage site. Binding characteristics indicate that the enzyme interacts efficiently with both single‐stranded and double‐stranded substrates containing strong topoisomerase I sites (STS), a unique property not shared by any other type I topoisomerase. The oligonucleotides containing STS effectively inhibit the M. smegmatistopoisomerase I DNA relaxation activity. |
| Databáze: |
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