Related Experiment Video
Updated: Jun 26, 2026

In Vitro Directed Evolution of a Restriction Endonuclease with More Stringent Specificity
Published on: March 25, 2020
Directed evolution of homing endonuclease I-SceI with altered sequence specificity
Zhilei Chen1, Fei Wen, Ning Sun
1Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
Researchers engineered homing endonucleases for genome editing. A novel selection system evolved mutant I-SceI enzymes with enhanced DNA cleavage activity for new targets, improving genome targeting efficiency.
Area of Science:
- Molecular Biology
- Biotechnology
- Genomics
Background:
- Homing endonucleases are enzymes that recognize specific DNA sequences.
- They create double-stranded breaks, stimulating homologous recombination for genome editing.
- Directed evolution can alter their DNA cleavage specificity.
Purpose of the Study:
- To evolve mutant homing endonucleases with altered DNA cleavage specificity.
- To test the efficacy of a two-plasmid selection system for engineering homing endonucleases.
- To identify novel homing endonuclease variants for genome targeting.
Main Methods:
- Utilized a two-plasmid selection system coupling DNA cleavage with host cell survival.
- Employed directed evolution, including saturation mutagenesis, to modify I-SceI homing endonuclease.
- Assessed cleavage activity and specificity of evolved mutants against new DNA targets.
Main Results:
- Successfully evolved mutant I-SceI enzymes with significantly increased cleavage activity on a new 4 bp altered target sequence.
- The most evolved mutant exhibited ~100-fold higher survival rate compared to wild-type I-SceI.
- Mutant selectivity for the new target was comparable to wild-type I-SceI for its natural sequence.
Conclusions:
- The selection system is effective and efficient for engineering homing endonucleases with novel specificities.
- Evolved mutant I-SceI can be used for in vivo targeting of specific genomic DNA sequences.
- This work advances the potential of homing endonucleases in precise genome editing applications.
More Related Videos
11:37Using Sniper-Cas9 to Minimize Off-target Effects of CRISPR-Cas9 Without the Loss of On-target Activity Via Directed Evolution
Published on: February 26, 2019
08:37A Rapid and Facile Pipeline for Generating Genomic Point Mutants in C. elegans Using CRISPR/Cas9 Ribonucleoproteins
Published on: April 30, 2018
Related Concept Videos
Conservative Site-specific Recombination and Phase Variation
The recognition sites for Cre recombinase called LoxP...
Restriction Enzymes
The host bacteria protect their own genomic DNA from these enzymes by methylating these sites. Some...
Homologous Recombination
CRISPR/Cas9 Genome Editing