Single-molecule observations of topotecan-mediated TopIB activity at a unique DNA sequence.
Nucleic Acids Res
; 36(7): 2301-10, 2008 Apr.
Article
em En
| MEDLINE
| ID: mdl-18292117
ABSTRACT
The rate of DNA supercoil removal by human topoisomerase IB (TopIB) is slowed down by the presence of the camptothecin class of antitumor drugs. By preventing religation, these drugs also prolong the lifetime of the covalent TopIB-DNA complex. Here, we use magnetic tweezers to measure the rate of supercoil removal by drug-bound TopIB at a single DNA sequence in real time. This is accomplished by covalently linking camptothecins to a triple helix-forming oligonucleotide that binds at one location on the DNA molecule monitored. Surprisingly, we find that the DNA dynamics with the TopIB-drug interaction restricted to a single DNA sequence are indistinguishable from the dynamics observed when the TopIB-drug interaction takes place at multiple sites. Specifically, the DNA sequence does not affect the instantaneous supercoil removal rate or the degree to which camptothecins increase the lifetime of the covalent complex. Our data suggest that sequence-dependent dynamics need not to be taken into account in efforts to develop novel camptothecins.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
DNA Super-Helicoidal
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Topotecan
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Inibidores Enzimáticos
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Inibidores da Topoisomerase I
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Antineoplásicos
Idioma:
En
Ano de publicação:
2008
Tipo de documento:
Article