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Published on: December 26, 2020
Hyper(ADP-ribosyl)ation of histone H1
Canadian Journal of Biochemistry
|December 1, 1982
Summary
Poly(ADP-ribose) polymerase activity is highest in small chromatin fragments, with histone H1 being the primary target for poly(ADP-ribosyl)ation. This modification affects histone H1 mobility and is dependent on time and NAD+ concentration.
Area of Science:
- Biochemistry
- Molecular Biology
- Chromatin Structure
Background:
- Poly(ADP-ribose) polymerase (PARP) plays a crucial role in DNA repair and chromatin remodeling.
- Histones are the core components of nucleosomes, organizing DNA within the nucleus.
- Understanding PARP activity and its substrate specificity is vital for elucidating cellular regulatory mechanisms.
Purpose of the Study:
- To investigate the relationship between chromatin structure and poly(ADP-ribose) polymerase activity.
- To identify the specific histone proteins modified by poly(ADP-ribose) polymerase.
- To characterize the modification process and its impact on histone properties.
Main Methods:
- Mild micrococcal nuclease digestion of pancreatic nuclei to generate chromatin fragments of varying lengths.
- Electrophoresis of [32P]ADP-ribosylated histones using multi-dimensional gel systems (acid-urea, acid-urea-Triton, acid-urea-cetyltriammonium bromide).
- Selective extraction of histone H1 using 5% perchloric acid.
Main Results:
- Maximal poly(ADP-ribose) polymerase activity was observed in trimeric to tetrameric chromatin fragments.
- Histone H1 was identified as the primary substrate for poly(ADP-ribosyl)ation, with minimal modification of histone H1(0).
- Poly(ADP-ribosyl)ation of histone H1 proportionally retarded its electrophoretic mobility, revealing at least 12 distinct modification intermediates. Modification is time-dependent, favored by high NAD+ concentrations, and unaffected by Triton X-100.
Conclusions:
- Histone H1 is the principal target of poly(ADP-ribosyl)ation in pancreatic nuclei.
- The extent of poly(ADP-ribosyl)ation directly impacts histone H1 electrophoretic mobility.
- Chromatin structure influences poly(ADP-ribose) polymerase activity, with optimal activity observed in smaller oligomers.
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