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Published on: January 26, 2018
Modulation of chromatin structure by poly(ADP-ribosyl)ation
G de Murcia1, A Huletsky, G G Poirier
1Institut de biologie moléculaire et cellulaire, Laboratoire de biochimie II, France.
Summary
DNA breaks activate poly(ADP-ribose) polymerase (PARP) to modify histones, altering chromatin structure. This reversible process enhances DNA accessibility for repair enzymes.
Area of Science:
- Molecular Biology
- Biochemistry
- Epigenetics
Background:
- Poly(ADP-ribose) polymerase (PARP) is a conserved nuclear enzyme activated by DNA strand breaks.
- PARP activity is crucial for cellular responses to DNA damage.
Purpose of the Study:
- To investigate the effect of PARP activation on chromatin structure.
- To elucidate the role of histone modification in DNA repair accessibility.
Main Methods:
- In vitro studies of chromatin superstructure condensation and decondensation.
- Analysis of histone modification, specifically hyper(ADP-ribosy)ation.
- Investigation of DNA-histone interactions in core particles.
Main Results:
- PARP activation leads to chromatin decondensation, primarily through histone H1 hyper(ADP-ribosy)ation.
- Histone H2B modification in core particles causes partial DNA dissociation.
- Poly(ADP-ribosyl)ation-induced chromatin changes are reversible by poly(ADP-ribose) glycohydrolase.
Conclusions:
- DNA breaks during repair activate PARP, leading to poly(ADP-ribosyl)ation of histone H1.
- This modification opens the 25-nm chromatin fiber, increasing DNA accessibility for repair enzymes.
- The described mechanism is a rapid and reversible process essential for efficient DNA repair.
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