PMID:7559540
| Citation |
Zhang, HL, Malpure, S and DiGate, RJ (1995) Escherichia coli DNA topoisomerase III is a site-specific DNA binding protein that binds asymmetrically to its cleavage site. J. Biol. Chem. 270:23700-5 |
|---|---|
| Abstract |
The binding of DNA topoisomerase III (Topo III) to a single-stranded DNA substrate containing a strong cleavage site has been examined. The minimal substrate requirement for Topo III-catalyzed cleavage has been determined to consist of 7 bases; 6 bases 5' to the cleavage site and only 1 base 3' to the site. Nuclease P1 protection experiments indicate that the enzyme also binds to its substrate asymmetrically, protecting approximately 12 bases 5' to the cleavage site and only 2 bases 3' to the cleavage site. A catalytically inactive mutant of Topo III shows the same protection pattern as the active polypeptide, indicating that Topo III is a site-specific binding protein as well as a topoisomerase. Consistent with this view, an oligonucleotide containing a cleavage site is a more effective inhibitor and is bound more efficiently by Topo III than an oligonucleotide without a cleavage site. |
| Links | |
| Keywords |
Base Sequence; Binding Sites; DNA Topoisomerases, Type I/metabolism; DNA, Bacterial/genetics; DNA, Bacterial/metabolism; DNA, Single-Stranded/genetics; DNA, Single-Stranded/metabolism; DNA, Superhelical/chemistry; DNA, Superhelical/genetics; DNA, Superhelical/metabolism; DNA-Binding Proteins/metabolism; Escherichia coli/enzymology; Escherichia coli/genetics; Models, Biological; Molecular Sequence Data; Nucleic Acid Conformation; Oligodeoxyribonucleotides/genetics; Oligodeoxyribonucleotides/metabolism; Substrate Specificity |
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