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Biochemical Assays for Analyzing Activities of ATP-dependent Chromatin Remodeling Enzymes
Published on: October 25, 2014
Nucleosome recognition and spacing by chromatin remodelling factor ISW1a
1ETH Zürich, Institute of Molecular Biology and Biophysics, Schafmattstrasse 20, CH-8093 Zürich, Switzerland. richmond@mol.biol.ethz.ch
Biochemical Society Transactions
|March 23, 2012
Summary
ATP-dependent chromatin remodeling factors like ISW1a actively position nucleosomes. Structural modeling reveals how ISW1a may generate ordered nucleosome arrays, with DNA sequence potentially guiding promoter interactions.
Area of Science:
- Molecular Biology
- Structural Biology
- Genetics
Background:
- Nucleosomes are fundamental units of DNA packaging in eukaryotes.
- ATP-dependent chromatin remodelers actively alter nucleosome positions.
- Understanding the mechanisms of chromatin remodeling is crucial for gene regulation.
Purpose of the Study:
- To elucidate the structural mechanism of the ISW1a chromatin remodeler from Saccharomyces cerevisiae.
- To investigate the role of DNA sequence in nucleosome recognition by ISW1a.
- To model how ISW1a generates ordered nucleosome arrays.
Main Methods:
- X-ray crystallography of ISW1a (ΔATPase) with and without DNA.
- Cryo-electron microscopy (cryo-EM) of ISW1a (ΔATPase) bound to nucleosomes.
- Site-directed photo-cross-linking analyses in solution.
Main Results:
- A structural model of ISW1a complexed with a dinucleosome substrate was developed.
- The structure suggests DNA sequence influences nucleosome recognition and promoter specificity.
- The model explains the generation of ordered nucleosome arrays observed in genes and promoters.
Conclusions:
- ISW1a plays a key role in actively positioning nucleosomes.
- DNA sequence-dependent recognition contributes to the specificity of ISW1a's function.
- The findings provide insights into the generation of regular chromatin structures essential for genome organization.
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