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Molecular interactions between DNA, poly(ADP-ribose) polymerase, and histones
1Department of Pharmacology, University of California, School of Medicine, San Francisco 94143-0130.
The Journal of Biological Chemistry
|January 25, 1988
Summary
Poly(ADP-ribose) polymerase and histones cooperatively bind DNA, influencing its structure. This interaction, crucial for DNA topology, is modulated by enzyme activity and auto-ADP-ribosylation.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- Poly(ADP-ribose) polymerase (PARP) plays a role in DNA repair and chromatin remodeling.
- Histones are fundamental proteins involved in DNA packaging and regulation.
- Understanding protein-DNA interactions is key to deciphering gene regulation and cellular processes.
Purpose of the Study:
- To investigate the molecular interactions of poly(ADP-ribose) polymerase (PARP) with DNA and histones.
- To determine how PARP and histones cooperatively affect DNA topology.
- To elucidate the role of PARP activity in modulating DNA structure.
Main Methods:
- Nitrocellulose filter binding assays were used to quantify molecular interactions.
- Studies involved purified PARP, whole thymus histones, histone H1, genomic DNA, and SV40 DNA (circular and linearized).
- DNA topology changes, including superhelicity induction, were analyzed.
Main Results:
- PARP and histones exhibited significantly augmented binding to DNA when present together.
- PARP associated with histones independently of DNA.
- Cooperative binding to relaxed circular DNA was greater than to linearized DNA, and PARP binding induced superhelicity.
- PARP's influence on DNA topology was reversed by auto-ADP-ribosylation or inhibited by benzamide.
Conclusions:
- PARP and histones form cooperative complexes with DNA, significantly impacting DNA topology.
- PARP's enzymatic activity is critical for its role in DNA structural modulation.
- These findings highlight the intricate interplay between PARP, histones, and DNA structure.