Related Experiment Videos
DNA supercoiling by core histone fractions and protamine
Molecular Biology Reports
|January 1, 1984
Summary
Nuclear extracts from fruit fly embryos contain DNA topoisomerase 1 and nuclease enzymes. These enzymes help supercoil DNA with specific histone proteins, but not with histone HI.
Area of Science:
- Biochemistry
- Molecular Biology
- Genetics
Background:
- Nuclear extracts from late Drosophila melanogaster embryos possess enzymatic activities.
- DNA topoisomerase 1 and nuclease activities are present in these extracts.
Purpose of the Study:
- To investigate the DNA supercoiling activity of nuclear extracts.
- To determine the role of histone proteins in DNA supercoiling facilitated by these extracts.
Main Methods:
- Isolation of nuclear extract from late Drosophila melanogaster embryos.
- Assay for Mg2+-dependent DNA topoisomerase 1 and nuclease activities.
- Supercoiling assays using closed circular duplex DNA in the presence of various histone fractions and protamine.
Main Results:
- The nuclear extract exhibited Mg2+-dependent DNA topoisomerase 1 and nuclease activities.
- DNA supercoiling was facilitated by calf histone fractions (H2A, H2B, H3, H4) and fish protamine.
- Histone HI did not support the DNA supercoiling activity.
Conclusions:
- Drosophila melanogaster nuclear extracts contain essential enzymatic machinery for DNA topology modulation.
- Specific histone proteins (H2A, H2B, H3, H4) and protamine play a role in facilitating DNA supercoiling, suggesting differential roles in chromatin structure.