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Defining the seed sequence of the Cas12b CRISPR-Cas effector complex
Ishita Jain1,2, Leonid Minakhin1, Vladimir Mekler1
1a Department of Rutgers University, Rutgers The State University of New Jersey, Waksman Institute of Microbiology , Piscataway , NJ , USA.
RNA Biology
|July 20, 2018
Summary
Researchers identified a short seed sequence in CRISPR-Cas12b effectors. An additional specificity determinant at the cleavage site compensates for potential off-target activity, enabling specialized genome editing.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- CRISPR-Cas systems mediate targeted DNA manipulation through PAM recognition and guide RNA interaction.
- Off-target activity in CRISPR-Cas effectors arises from mismatches outside the essential seed sequence.
- Understanding effector-target recognition is crucial for advancing genome editing technologies.
Purpose of the Study:
- To define the seed sequence and target recognition mechanism of the Type V Cas12b effector.
- To investigate the role of the cleavage site nucleotide in Cas12b target binding specificity.
- To assess the potential of Cas12b for specialized genome editing applications.
Main Methods:
- Biochemical assays to characterize Cas12b effector binding to target DNA.
- Analysis of CRISPR RNA-Cas12b interactions and the impact of sequence variations.
- Comparative analysis of Cas12b effectors from different bacterial species.
Main Results:
- The Cas12b seed sequence was determined to be five bases long, shorter than other characterized effectors.
- The nucleotide at the target cleavage site significantly influences Cas12b binding affinity and specificity.
- Cas12b effectors from Bacillus thermoamylovorans and Alicyclobacillus acidoterrestris share this specificity determinant.
Conclusions:
- Cas12b possesses a short seed sequence potentially leading to promiscuity.
- An additional specificity determinant at the cleavage site compensates for the short seed, enhancing precision.
- Cas12b's unique recognition properties make it suitable for specialized genome editing applications.
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