Dataset Information

Role of Flexibility in Protein-DNA-Drug Recognition: The Case of Asp677Gly-Val703Ile Topoisomerase Mutant Hypersensitive to Camptothecin.

ABSTRACT: Topoisomerases I are ubiquitous enzymes that control DNA topology within the cell. They are the unique target of the antitumor drug camptothecin that selectively recognizes the DNA-topoisomerase covalent complex and reversibly stabilizes it. The biochemical and structural-dynamical properties of the Asp677Gly-Val703Ile double mutant with enhanced CPT sensitivity have been investigated. The mutant displays a lower religation rate of the DNA substrate when compared to the wild-type protein. Analyses of the structural dynamical properties by molecular dynamics simulation show that the mutant has reduced flexibility and an active site partially destructured at the level of the Lys532 residue. These results demonstrate long-range communication mechanism where reduction of the linker flexibility alters the active site geometry with the consequent lowering of the religation rate and increase in drug sensitivity.

SUBMITTER: D'Annessa I

PROVIDER: S-EPMC3270393 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Publications

Role of Flexibility in Protein-DNA-Drug Recognition: The Case of Asp677Gly-Val703Ile Topoisomerase Mutant Hypersensitive to Camptothecin.

D'Annessa Ilda I Tesauro Cinzia C Fiorani Paola P Chillemi Giovanni G Castelli Silvia S Vassallo Oscar O Capranico Giovanni G Desideri Alessandro A

Journal of amino acids 20120119

Topoisomerases I are ubiquitous enzymes that control DNA topology within the cell. They are the unique target of the antitumor drug camptothecin that selectively recognizes the DNA-topoisomerase covalent complex and reversibly stabilizes it. The biochemical and structural-dynamical properties of the Asp677Gly-Val703Ile double mutant with enhanced CPT sensitivity have been investigated. The mutant displays a lower religation rate of the DNA substrate when compared to the wild-type protein. Analys ...[more]

PMID: 22315664

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Project description:DNA topoisomerase I (Top1) and topoisomerase II (Top2) inhibitors are widely used to treat a variety of cancers. Their mechanism of action involves stabilization of otherwise transient ("cleavable") complexes between Top1 or Top2 and DNA; collisions of DNA replication forks with such stabilized complexes lead to formation of DNA double-strand breaks (DSBs). In this study, using 5-ethynyl-2'deoxyuridine (EdU) as a DNA precursor, we directly assessed the relationship between DNA replication and induction of DSBs revealed as ?H2AX foci in A549 cells treated with Top1 inhibitors topotecan (Tpt) or camptothecin (Cpt) and Top2 inhibitors mitoxantrone (Mxt) and etoposide (Etp). Analysis of cells by multiparameter laser scanning cytometry following treatment with Tpt or Cpt revealed that only DNA replicating cells showed induction of ?H2AX and a strong correlation between DNA replication and formation of DSBs (r = 0.86). In cells treated with Mxt or Etp, the correlation was weaker (r = 0.52 and 0.64). In addition, both Mtx and Etp caused induction of ?H2AX in cells not replicating DNA. Confocal imaging of nuclei of cells treated with Tpt revealed the presence of ?H2AX foci predominantly in DNA replicating cells and close association and co-localization of ?H2AX foci with DNA replication sites. In cells treated with Mxt or Etp, the ?H2AX foci were induced in DNA replicating as well as non-replicating cells but the close association between a large proportion of ?H2AX foci and DNA replication sites was also apparent. The data are consistent with the view that collision of DNA replication forks with cleavable Top1-DNA complexes stabilized by Tpt/Cpt is the sole cause of induction of DSBs. Additional mechanisms such as involvement of transcription and/or generation of oxidative stress may contribute to DSBs induction by Mxt and Etp. The confocal analysis of the association between DNA replication sites and the sites of DSBs (?H2AX foci) opens a new approach for mechanistic studies of the involvement of DNA replication in induction of DNA damage.

Dataset Information

Role of Flexibility in Protein-DNA-Drug Recognition: The Case of Asp677Gly-Val703Ile Topoisomerase Mutant Hypersensitive to Camptothecin.

Publications

Role of Flexibility in Protein-DNA-Drug Recognition: The Case of Asp677Gly-Val703Ile Topoisomerase Mutant Hypersensitive to Camptothecin.

Similar Datasets

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