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Role of magnesium ions in DNA recognition by the EcoRV restriction endonuclease

Mai Zahran1, Tomasz Berezniak, Petra Imhof

  • 1Computational Molecular Biophysics, IWR, University of Heidelberg, Heidelberg, Germany.

FEBS Letters
|August 13, 2011
PubMed

Insights

The second magnesium ion (Mg(B)2+) is essential for the restriction enzyme EcoRV to bind DNA tightly and adopt a cleavage-ready shape. Without Mg(B)2+, DNA binding is weak and cleavage is unlikely.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Structural Biology

Background:

  • Restriction endonuclease EcoRV utilizes two magnesium ions for DNA cleavage.
  • The precise role of the second magnesium ion, Mg(B)2+, remains under investigation.

Purpose of the Study:

  • To elucidate the function of the second magnesium ion (Mg(B)2+) in EcoRV-mediated DNA cleavage.
  • To investigate the structural and conformational changes induced by the presence or absence of Mg(B)2+.

Main Methods:

  • Multiple independent molecular dynamics simulations were employed.
  • Analysis focused on protein-DNA interactions, hydrogen bond networks, and active site conformations.

Main Results:

  • Mg(B)2+ is critical for establishing a stable EcoRV-DNA complex.
  • The absence of Mg(B)2+ disrupts the protein-DNA hydrogen bond network.
  • Loss of Mg(B)2+ prevents the formation of the characteristic DNA kink and hinders active site residue rearrangement necessary for catalysis.

Conclusions:

  • Mg(B)2+ plays a crucial role in stabilizing the EcoRV-DNA complex conformation required for DNA hydrolysis.
  • The findings clarify the function of the second magnesium ion in the catalytic mechanism of EcoRV.

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