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Inhibition of Mycobacterium smegmatis topoisomerase I by specific oligonucleotides
Author(s) -
Bhaduri Tisha,
Basak Shashwati,
Sikder Devanjan,
Nagaraja Valakunja
Publication year - 2000
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(00)02261-4
Subject(s) - topoisomerase , mycobacterium smegmatis , oligonucleotide , dna , nuclease , biochemistry , nucleotide , binding site , biology , microbiology and biotechnology , dna footprinting , chemistry , dna binding protein , gene , transcription factor , mycobacterium tuberculosis , medicine , pathology , tuberculosis
DNA topoisomerase I from Mycobacterium smegmatis unlike 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 coli topoisomerase I and III. P1 nuclease and KMnO 4 footprinting 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. smegmatis topoisomerase I DNA relaxation activity.