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Updated: May 8, 2026
09:53
Single-Molecule Dwell-Time Analysis of Restriction Endonuclease-Mediated DNA Cleavage
Published on: February 7, 2021
Structural analysis of DNA-protein complexes regulating the restriction-modification system Esp1396I
Richard N A Martin1, John E McGeehan, Neil J Ball
1Institute of Biomedical and Biomolecular Science, University of Portsmouth, King Henry I Street, Portsmouth, Hampshire PO1 2DY, England.
Summary
The Esp1396I controller protein regulates gene expression by binding DNA. Unbound DNA naturally bends, and its major groove widens when bound by the protein, aiding complex formation.
Area of Science:
- Molecular Biology
- Structural Biology
- Genetics
Background:
- Type II restriction-modification (RM) systems use controller proteins to regulate gene expression.
- The Esp1396I RM system's controller protein (C-protein) binds distinct DNA operator sequences.
- Previous studies detailed C-protein binding affinities to operator sites.
Purpose of the Study:
- To investigate the structural basis of DNA bending in unbound operator sequences.
- To elucidate the DNA structural changes induced by C-protein binding.
- To understand the mechanism of cooperative binding in forming repression complexes.
Main Methods:
- X-ray crystallography to obtain protein-DNA co-crystal structures.
- Analysis of unbound DNA structures within protein-DNA complexes.
- Comparative structural analysis of bound and unbound DNA states.
Main Results:
- Two co-crystal structures of C-protein with portions of unbound DNA were determined.
- Unbound DNA exhibited significant distortion and bending between conserved sequences.
- Increased major groove width adjacent to bound C-protein dimers was observed.
Conclusions:
- Naked operator DNA possesses an intrinsic propensity to bend.
- DNA distortion facilitates cooperative binding of C-protein dimers.
- Structural insights explain the formation of the tetrameric repression complex.
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