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EcoRV restriction endonuclease: communication between DNA recognition and catalysis.
C L Vermote1, I B Vipond, S E Halford
1Department of Biochemistry, University of Bristol, U.K.
Biochemistry
|July 7, 1992
Summary
Mutating Asn185 or Asn188 in EcoRV restriction enzyme did not affect DNA binding but reduced Mg2+ activity while retaining Mn2+ activity, revealing distinct DNA recognition and catalytic functions.
Area of Science:
- Molecular Biology
- Biochemistry
- Structural Biology
Background:
- EcoRV restriction endonuclease recognizes and cleaves specific DNA sequences.
- Understanding the structure-function relationship of restriction enzymes is crucial for molecular biology applications.
Purpose of the Study:
- To investigate the roles of Asn185 and Asn188 in EcoRV function.
- To elucidate the relationship between DNA recognition and catalytic activity in EcoRV.
Main Methods:
- Constructed a genetic system for EcoRV mutagenesis and protein overproduction.
- Created EcoRV mutants with Ala replacing Asn185 or Asn188.
- Assessed DNA binding affinity and cleavage activity with different metal ion cofactors (Mg2+, Mn2+).
Main Results:
- Mutations did not affect DNA binding affinity for EcoRV mutants.
- Mutants showed severely depressed cleavage activity with Mg2+ but retained activity with Mn2+.
- Mutant enzymes exhibited lower affinity for Mg2+ but not Mn2+ when bound to DNA.
Conclusions:
- The DNA recognition residues (Asn185, Asn188) are critical for organizing catalytic functions.
- Distinct functional locations for DNA recognition and catalysis exist within the EcoRV enzyme.
- Metal ion cofactor preference is influenced by the specific amino acid residues involved in DNA recognition.