Deoxyribonuclease I sensitivity of DNA replicated in permeable mouse sarcoma cells
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Abstract:
To study chromatin structure at the sites of DNA replicated in permeable cells, deoxyribonuclease I (DNase I) sensitivity of newly replicated DNA in permeable mouse sarcoma cells was compared with that of newly replicated DNA in intact cells. About 35% of the DNA replicated in permeable cells was hypersensitive to DNase I, and the remaining DNA showed the same DNase I sensitivity as that of parental chromatin DNA. The sensitivity of DNA replicated in permeable cells was higher than that of DNA newly replicated in intact cells, and was close to that of DNA replicated in the presence of cycloheximide. The sensitivity of DNA pulse-labeled with [3H]deoxythymidine triphosphate by replication in permeable cells was reduced significantly by chasing with cold deoxythymidine triphosphate. The present results suggest that chromatin structure at the sites of DNA replicated in permeable cells is similar to that at the sites of DNA replicated in living cells in the absence of protein synthesis, and that some structural change (possibly toward the maturation) of newly replicated chromatin occurs after the DNA replication in permeable cells.
Insights
Chromatin structure of newly replicated DNA in permeable cells resembles that in living cells without protein synthesis. Further maturation occurs post-replication in permeable cells, impacting DNA accessibility.
Area of Science:
- Molecular Biology
- Cell Biology
- Chromatin Structure
Background:
- Understanding chromatin structure during DNA replication is crucial for cell cycle regulation.
- Permeable cell systems offer a model to study DNA replication and chromatin assembly.
- Deoxyribonuclease I (DNase I) sensitivity is a key indicator of chromatin accessibility.
Purpose of the Study:
- To investigate the chromatin structure of newly replicated DNA in permeable mouse sarcoma cells.
- To compare the DNase I sensitivity of DNA replicated in permeable cells versus intact cells.
- To elucidate the post-replication structural changes in newly synthesized chromatin.
Main Methods:
- Comparison of DNase I sensitivity between newly replicated DNA in permeable and intact mouse sarcoma cells.
- Pulse-labeling of DNA with [3H]deoxythymidine triphosphate in permeable cells.
- Chasing experiments with cold deoxythymidine triphosphate to assess DNA maturation.
Main Results:
- Approximately 35% of DNA replicated in permeable cells exhibited hypersensitivity to DNase I.
- DNA replicated in permeable cells showed higher DNase I sensitivity than in intact cells.
- Sensitivity decreased upon chasing with cold deoxythymidine triphosphate, indicating structural changes.
Conclusions:
- Chromatin structure at replication sites in permeable cells mirrors that in living cells lacking protein synthesis.
- Newly replicated chromatin undergoes structural maturation after DNA replication in permeable cells.
- Permeable cell systems provide insights into dynamic chromatin assembly and remodeling processes.