Nuclease sensitivity of active chromatin

Area of Science:

• Molecular Biology
• Chromatin Structure
• Gene Expression

Background:

• Active gene regions exhibit distinct chromatin structures.
• Understanding nuclease sensitivity is crucial for characterizing active chromatin.

Purpose of the Study:

• To investigate the nuclease sensitivity of active genes in chicken erythrocyte nuclei.
• To identify factors contributing to DNase I and micrococcal nuclease accessibility in active chromatin.

Main Methods:

• DNase I nick translation for labeling active regions.
• Micrococcal nuclease digestion to assess chromatin solubilization and internucleosomal cutting.
• Isolation and digestion of mononucleosomes.

Main Results:

• DNase I specifically attacks active genes.
• Micrococcal nuclease preferentially cuts internucleosomal regions of active genes, enriching mononucleosomes with active gene DNA.
• Isolated active mononucleosomes show preferential DNase I sensitivity.
• High-mobility group proteins are essential for DNase I sensitivity but not micrococcal nuclease accessibility.

Conclusions:

• Active genes share a common conformation making them accessible to nucleases.
• This conformation is a general feature of all active genes, irrespective of expression level.
• Chromatin structure analysis techniques allow study of the entire active gene population.