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Updated: Jun 6, 2026
06:48
CD Spectroscopy to Study DNA-Protein Interactions
Published on: February 10, 2022
Domain swapping in allosteric modulation of DNA specificity
Chad K Park1, Hemant K Joshi, Alka Agrawal
1Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona, United States of America.
Plos Biology
|December 15, 2010
Summary
The restriction enzyme SgrAI forms a tetramer through domain swapping, which is crucial for its allosteric self-modulation of DNA cleavage activity and sequence specificity.
Area of Science:
- Molecular Biology
- Structural Biology
- Enzymology
Background:
- SgrAI is a type IIF restriction endonuclease with unique properties.
- It exhibits allosteric self-modulation of cleavage activity and sequence specificity.
- Previous studies showed DNA-bound SgrAI dimers oligomerize to enhance DNA cleavage rates.
Purpose of the Study:
- To determine the structural basis of SgrAI's allosteric regulation.
- To investigate the oligomerization of SgrAI upon DNA binding.
- To elucidate the mechanism behind SgrAI's unusual cleavage activity and specificity.
Main Methods:
- X-ray crystallography of SgrAI bound to DNA and Ca(2+).
- Site-directed mutagenesis of SgrAI (P27W and P27G mutations).
- Analysis of DNA cleavage rates and oligomerization states.
Main Results:
- A novel tetrameric structure of SgrAI bound to DNA was determined, involving N-terminal domain swapping.
- This tetrameric form is distinct from homologous enzymes like Cfr10I and NgoMIV.
- Mutations P27W and P27G disrupted tetramer formation and abolished allosteric stimulation of DNA cleavage.
Conclusions:
- Domain swapping of the N-terminal residues is essential for SgrAI oligomerization and allosteric regulation.
- The tetrameric SgrAI structure provides a mechanistic explanation for its unique cleavage properties.
- Further association of tetramers may lead to higher-order oligomers, influencing SgrAI function.
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