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Substrate Generation for Endonucleases of CRISPR/Cas Systems
Published on: September 8, 2012
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Optimized protocols for the characterization of Cas12a activities
Lindsie Martin1, Saadi Rostami1, Rakhi Rajan1
1Department of Chemistry and Biochemistry, Price Family Foundation Institute of Structural Biology, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, OK, United States.
Methods in Enzymology
|January 22, 2023
Summary
This study details protocols for purifying CRISPR-associated protein 12a (Cas12a) and transcribing its guide RNA. These methods enable in vitro studies of Cas12a DNA cleavage activities for gene editing and diagnostics.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- CRISPR-associated (Cas) Cas12a is a key effector protein in type V-A CRISPR systems.
- Cas12a is a sequence-specific endonuclease utilized for gene editing and medical diagnostics due to its programmable guide RNA and DNA cleavage activity.
- Compared to Cas9, Cas12a offers advantages like a smaller size and staggered DNA cleavage, promoting cellular recombination.
Purpose of the Study:
- To provide detailed protocols for the recombinant purification of the Cas12a protein.
- To outline methods for transcribing the programmable CRISPR RNA (crRNA) for Cas12a.
- To establish in vitro assays for studying Cas12a's cis, trans, and guide-RNA independent DNA cleavage activities.
Main Methods:
- Recombinant purification of Cas12a protein.
- In vitro transcription of programmable crRNA.
- Development of in vitro activity assays for Cas12a, including cis, trans, and guide-RNA independent cleavage.
- Quantification of assay data using ImageJ and rate constant calculations using MATLAB.
Main Results:
- Established protocols for Cas12a purification and crRNA transcription.
- Demonstrated various in vitro DNA cleavage activities of Cas12a with different substrates.
- Provided methods for quantitative analysis of Cas12a activity assays.
Conclusions:
- The presented protocols facilitate comprehensive in vitro characterization of Cas12a.
- These methods support further structural and mechanistic investigations of Cas12a and related Cas proteins.
- The optimized protocols are valuable for advancing gene editing and diagnostic applications of Cas12a.
