Related Experiment Videos
Directed evolution of restriction endonuclease BstYI to achieve increased substrate specificity
James C Samuelson1, Shuang-yong Xu
1New England Biolabs, 32 Tozer Road, Beverly, MA 01915, USA.
Journal of Molecular Biology
|June 11, 2002
Summary
Researchers engineered the BstYI restriction enzyme to specifically cleave AGATCT sequences. This modified enzyme, NN1, shows a 12-fold preference, advancing protein engineering strategies for altered enzyme specificity.
Area of Science:
- Molecular Biology
- Enzymology
- Protein Engineering
Background:
- Restriction endonucleases are crucial for DNA manipulation but challenging to engineer for altered substrate specificity.
- The thermophilic restriction endonuclease BstYI recognizes a degenerate hexanucleotide sequence (5'-R GATCY-3').
- Understanding substrate recognition in degenerate-sequence-recognizing enzymes is limited.
Purpose of the Study:
- To investigate and engineer the substrate specificity of the BstYI restriction endonuclease.
- To increase the enzyme's specificity towards the AGATCT sequence.
Main Methods:
- A novel genetic selection and screening process was employed.
- Modification of Escherichia coli host genomic DNA using BglII N4-cytosine methyltransferase to protect specific sites.
- Identification and combination of amino acid substitutions to create a superior variant.
Main Results:
- Two BstYI variants with a preference for AGATCT cleavage were successfully isolated.
- A superior variant, NN1, was generated by combining key amino acid substitutions.
- NN1 exhibits a 12-fold increased preference for AGATCT over AGATCC or GGATCT, with no detected cleavage of GGATCC.
Conclusions:
- Laboratory evolution is a powerful strategy for engineering restriction endonuclease specificity.
- The developed BstYI variant NN1 demonstrates significantly enhanced and specific DNA cleavage.
- This work provides a foundation for designing enzymes with tailored substrate recognition profiles.