SCAN1 mutant Tdp1 accumulates the enzyme--DNA intermediate and causes camptothecin hypersensitivity
| Autor: | James J. Champoux, Heidrun Interthal, Jörg Zotzmann, Thomas E. Kehl-Fie, John B. Leppard, Hong Jing Chen |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
DNA repair
Mutant Biology General Biochemistry Genetics and Molecular Biology Article S Phase chemistry.chemical_compound Neoplasms medicine Humans Enzyme Inhibitors Molecular Biology General Immunology and Microbiology Phosphoric Diester Hydrolases General Neuroscience Topoisomerase Tyrosyl-DNA Phosphodiesterase 1 medicine.disease Flow Cytometry Molecular biology chemistry Amino Acid Substitution Mutation Spinocerebellar ataxia biology.protein Camptothecin TDP1 DNA medicine.drug |
| Zdroj: | The EMBO journal. 24(12) |
| ISSN: | 0261-4189 |
| Popis: | Tyrosyl-DNA phosphodiesterase (Tdp1) catalyzes the hydrolysis of the tyrosyl-3' phosphate linkage found in topoisomerase I-DNA covalent complexes. The inherited disorder, spinocerebellar ataxia with axonal neuropathy (SCAN1), is caused by a H493R mutation in Tdp1. Contrary to earlier proposals that this disease results from a loss-of-function mutation, we show here that this mutation reduces enzyme activity approximately 25-fold and importantly causes the accumulation of the Tdp1-DNA covalent reaction intermediate. Thus, the attempted repair of topoisomerase I-DNA complexes by Tdp1 unexpectedly generates a new protein-DNA complex with an apparent half-life of approximately 13 min that, in addition to the unrepaired topoisomerase I-DNA complex, may interfere with transcription and replication in human cells and contribute to the SCAN1 phenotype. The analysis of Tdp1 mutant cell lines derived from SCAN1 patients reveals that they are hypersensitive to the topoisomerase I-specific anticancer drug camptothecin (CPT), implicating Tdp1 in the repair of CPT-induced topoisomerase I damage in human cells. This finding suggests that inhibitors of Tdp1 could act synergistically with CPT in anticancer therapy. |
| Databáze: | OpenAIRE |
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