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Molecular implications of evolutionary differences in CHD double chromodomains.
John F Flanagan1, Bartlomiej J Blus, Daesung Kim
1Department of Biochemistry and Molecular Genetics, University of Virginia Health System, Charlottesville, VA 22908, USA.
Yeast CHD1 double chromodomains cannot bind histone H3 tails due to structural differences. This study reveals evolutionary specialization in CHD double chromodomains, impacting their targeting capabilities.
Area of Science:
- Biochemistry
- Structural Biology
- Molecular Biology
Background:
- CHD proteins are ATP-dependent chromatin remodelers involved in transcription.
- CHD1 double chromodomains in humans and Drosophila bind lysine 4-methylated histone H3, a mark of active chromatin.
- Differences exist in histone H3 tail binding among various CHD chromodomains.
Purpose of the Study:
- To present the crystal structure of yeast CHD1 double chromodomains.
- To compare the yeast structure with human CHD1 double chromodomains.
- To understand the evolutionary specialization and targeting capacities of CHD double chromodomains.
Main Methods:
- X-ray crystallography to determine the structure of yeast CHD1 double chromodomains.
- Comparative structural analysis between yeast and human CHD1 double chromodomains.
- Biochemical data interpretation to infer functional differences.
Main Results:
- The crystal structure of yeast CHD1 double chromodomains was determined.
- Key differences between yeast and human CHD1 double chromodomains were identified, particularly in residue orientation and insert structure.
- Yeast CHD1 double chromodomains lack the necessary structural features for methyllysine binding on histone H3 tails.
- Human CHD2 double chromodomains show reduced binding efficiency to methylated histone H3 tails compared to CHD1 due to insert variations.
Conclusions:
- Yeast CHD1 double chromodomains are structurally precluded from interacting with histone H3 tails.
- Evolutionary specialization has led to distinct targeting capacities among CHD double chromodomains.
- Structural variations explain the differential binding of methylated histone H3 tails by CHD proteins.
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