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High mobility group proteins 14 and 17 can space nucleosomes in vitro
1John Curtin School of Medical Research, Australian National University, Canberra, Australian Capital Territory.
The Journal of Biological Chemistry
|May 25, 1993
Summary
Researchers discovered that phosphorylated High Mobility Group (HMG) proteins 14 and 17, when added to histone octamers, create regularly spaced nucleosomes, mimicking chromatin structure in simple cells and active genes.
Area of Science:
- Molecular Biology
- Chromatin Structure
- Epigenetics
Background:
- Nucleosome spacing is crucial for gene regulation.
- Higher eukaryotic chromatin has irregularly spaced nucleosomes, unlike simpler organisms.
- High Mobility Group (HMG) proteins are implicated in chromatin organization.
Purpose of the Study:
- To identify factors responsible for regular nucleosome spacing.
- To investigate the role of HMG proteins in establishing chromatin structure.
- To understand the mechanism of generating regularly spaced nucleosomes.
Main Methods:
- Partial purification of an ATP-dependent spacing activity from Xenopus laevis ovaries.
- Testing various HMG proteins for their ability to influence nucleosome spacing.
- Utilizing two distinct nucleosome assembly systems for analysis.
Main Results:
- A novel ATP-dependent spacing activity was identified.
- Phosphorylated HMG proteins 14 and 17, when combined with histone octamers, generated regularly spaced nucleosomes (160-165 bp repeat length).
- This regular spacing is comparable to chromatin found in yeast and active genes.
Conclusions:
- Phosphorylated HMG 14 and 17 play a key role in establishing regular nucleosome spacing.
- The findings provide insights into the mechanisms of chromatin organization in higher eukaryotes.
- This research contributes to understanding the link between chromatin structure and gene accessibility.