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Histones H1 and H4 are present near the replication fork
V Stefanovsky1, S Dimitrov, V Russanova
1Institute of Molecular Biology, Bulgarian Academy of Sciences, Sofia.
Molecular Biology Reports
|November 1, 1990
Summary
Histones H1 and H4 are present at sites of DNA synthesis. These core proteins associate with newly synthesized DNA, suggesting their proximity to the replication fork during DNA replication.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Histones are crucial for DNA packaging and gene regulation.
- Understanding histone dynamics during DNA replication is essential for comprehending genome stability.
Purpose of the Study:
- To investigate the association of histones H1 and H4 with nascent DNA during replication.
- To determine the temporal presence of histones H1 and H4 at active DNA synthesis sites.
Main Methods:
- Ehrlich ascites tumor cells were pulse-labeled with 3H-thymidine.
- Formaldehyde crosslinking was used to fix histone-DNA interactions.
- Chromatin fragments were sonicated, purified via CsCl gradient, and immunoprecipitated using anti-histone H1 and H4 antibodies.
Main Results:
- Both histones H1 and H4 were found associated with nascent DNA.
- This association was observed even after a short 1-minute pulse labeling period.
- Specific radioactivity in immunoprecipitated probes confirmed histone presence at sites of DNA synthesis.
Conclusions:
- Histones H1 and H4 are present near the DNA replication fork.
- These histones play a role in the dynamic process of DNA replication and chromatin assembly.