Interactions between eukaryotic DNA topoisomerase I and a specific binding sequence

The interaction between eukaryotic DNA topoisomerase I and a high affinity binding sequence was investigated. Quantitative footprint analysis demonstrated that the substrate preference results from strong specific binding of topoisomerase I to the sequence. The specificity was conferred by a tight n...

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Bibliographic Details
Published in:The Journal of biological chemistry 1989-06, Vol.264 (17), p.10110-10113
Main Authors: Stevnsner, T, Mortensen, U H, Westergaard, O, Bonven, B J
Format: Article
Language:English
Subjects:
Animals
Base Sequence
DNA - metabolism
DNA Topoisomerases, Type I - metabolism
Kinetics
Methylation
Restriction Mapping
Substrate Specificity
Tetrahymena - enzymology
Tetrahymena thermophila
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Summary:The interaction between eukaryotic DNA topoisomerase I and a high affinity binding sequence was investigated. Quantitative footprint analysis demonstrated that the substrate preference results from strong specific binding of topoisomerase I to the sequence. The specificity was conferred by a tight noncovalent association between the enzyme and its target DNA, whereas the transient formation of a covalently bound enzyme·nicked DNA intermediate contributed insignificantly to the overall affinity. Topoisomerase I protected both strands over a 20-base pair region in which the cleavage site was centrally located. DNA modification interference analysis revealed a 16-base pair interference region on the scissile strand. Essential bases were confined to the 5′ side of the cleavage site. The 6-base pair interference region observed on the complementary strand did not contain essential bases.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(18)81773-2