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Apoptin protein multimers form distinct higher-order nucleoprotein complexes with DNA
Sirik R Leliveld1, Remus T Dame, Mieke A Mommaas
1Department of Chemistry, Leiden University, The Netherlands.
Nucleic Acids Research
|August 9, 2003
Summary
Apoptin, a protein from chicken anemia virus, selectively kills tumor cells by forming complexes with DNA. This interaction in tumor cells may disrupt DNA transcription and synthesis, leading to cell death.
Area of Science:
- Molecular Biology
- Virology
- Cell Biology
Background:
- Apoptin, derived from chicken anemia virus, is a tumor-specific cytotoxic agent.
- Apoptin functions as a stable multimeric complex of 30-40 monomers.
- Apoptin is imported into the nucleus of tumor cells, but not normal cells, preceding apoptosis induction.
Purpose of the Study:
- To investigate the subcellular localization and DNA-binding properties of apoptin in tumor cells.
- To elucidate the mechanism by which apoptin induces apoptosis in tumor cells.
Main Methods:
- Immunoelectron microscopy to determine apoptin localization within tumor cell nuclei.
- In vitro studies to analyze apoptin's interaction with DNA and formation of superstructures.
- Characterization of DNA-binding sites on apoptin multimers.
Main Results:
- Apoptin predominantly co-localizes with heterochromatin and nucleoli in tumor cells.
- Apoptin forms distinct superstructures with DNA in vitro, with a maximum diameter of 200 nm.
- Each apoptin multimer possesses eight DNA-binding sites that preferentially bind DNA strand ends.
Conclusions:
- Apoptin's affinity for DNA, particularly naked DNA and DNA ends, suggests in vivo superstructure formation.
- These DNA forms are associated with active transcription, replication, and damage.
- Apoptin may induce apoptosis by interfering with DNA transcription and synthesis in tumor cells.